Article: 222483 of rec.radio.amateur.antenna From: "Caveat Lector" References: Subject: Re: antenna theory for idiots? Message-ID: <6GeTf.12761$Uc2.5167@fed1read04> Date: Sun, 19 Mar 2006 07:22:38 -0800 Lisa: Check out the SWL oriented antenna links at URL: http://ac6v.com/swl.htm#ANT -- CL -- I doubt, therefore I might be ! "Lisa Simpson" wrote in message news:fg3Tf.33148$UZ5.20113@tornado.ohiordc.rr.com... > Can anyone point me at a good book or website that can teach me about > antenna theory from a beginner's standpoint? I'm getting into SWL & feel > I > really need to understand this subject well . . . > > Article: 222484 of rec.radio.amateur.antenna From: "Basil Burgess" Subject: Re: First Attempt Date: Sun, 19 Mar 2006 11:07:02 -0500 Message-ID: References: <1142741497.477575.13150@u72g2000cwu.googlegroups.com> Hello I'm sorry, though I tried to word that idea carefully, I left room for confusion. I wasn't trying to work DX, I only meant that the antenna received a clear signal from distant stations. I know that this is entirely due to the sensitivity and selectivity of my receiver, and does not reflect the ability to transmit to that distance. I had no expectation of getting out to the rest of the world. I'd have been happy to talk to someone 3 miles >from me, for a first QSO. Thank you for your ideas, though. 73 Basil VE3JEB "pbourget" wrote in message news:1142741497.477575.13150@u72g2000cwu.googlegroups.com... > > There is more to contacting DX then trying different antennas. You say > you are picking up DX from Europe so you obviously have a setup that > receives reasonably. How efficient it is transmitting is a different > issue. Can you make local contacts in Canada and the USA? > > I was just trying to contact CN2R in Morrocco on 80 meters. I could > hear him fine but he doesn't seem to hear me. Well I am running 100 > watts with a trap dipole. He probably can't hear me. He is also > probably running a kilowatt and I know he has great antennas. Much of > the DX you will hear may be running 10 times the power you are and that > is why you hear them and they don't hear you. Don't worry about the > antenna too much until you make local contacts and work your way out to > greater distances. > Also, you may have to call for a long time to get through the pileup > calling the DX (which you may not hear). Try calling CQ DX yourself and > see if anyone comes back. > > Pete W6OP > Article: 222485 of rec.radio.amateur.antenna From: "Lisa Simpson" References: <5pfTf.5294$TK2.2544@trnddc07> Subject: Re: Pirate radio's hip-hop tunes finding way to pilots' ears Message-ID: Date: Sun, 19 Mar 2006 17:48:30 GMT -- ================================= Earl W. Phillips, Jr. PHILLIPS DESIGN http://www.pdesign.net earl@pdesign.net 614.764.0476 - V Offering AFFORDABLE website development & maintenance! Protect your (Windows) computer with our "Stop 'Em Dead!" service! My calendar: http://calendar.yahoo.com/public/earlwphillipsjr "stananger" < stananger@********.***> wrote in message news:5pfTf.5294$TK2.2544@trnddc07... > Pirate radio's hip-hop tunes finding way to pilots' ears > > These days, pilots at Miami International Airport are hearing something > unexpected in their headphones: hip-hop from a pirate radio station. > BY DAVID OVALLE > dovalle@MiamiHerald.com > > It began with airline pilots reporting hip-hop songs playing on two > frequencies from a station calling itself Da Streetz. > > Authorities pinpointed the source of the transmission: a stucco-and-brick, > two-story warehouse in Opa-locka. Joseph Zeller, a state agent, discovered > a large radio antenna mounted on a tower next to the building. > > Armed with a search warrant, he confiscated three computers, a monitor, a > mixing board, a stereo compressor, a microphone, a two-deck CD player, a > telephone, a DSL modem, two stereo speakers, three gray three-ring binders > and 10 cases filled with CDs. > > But no radio transmitter. And no disc jockey. > > ''No arrests. This is still an open case,'' said Paige Patterson-Hughes, a > Florida Department of Law Enforcement spokeswoman. > > Meanwhile, Da Streetz remains on the air. > > The music from the pirate radio station has been so troublesome over the > last month that a federal engineer who specializes in frequency > transmissions has arrived in Miami to help investigators locate the signal. > > ''It's intermittent. Not all day, every day,'' said Kathleen Bergen, a > spokeswoman for the Federal Aviation Administration. ``But clear > communication between air control and the pilots is a critical part of > flying.'' > > Helping in the investigation: the Federal Communications Commission and the > Florida Department of Law Enforcement. > > It is believed to be the first such case worked by state agents in South > Florida since a new law gave law enforcement broader authority to go after > illegal radio stations. > > It's unclear if agents have a suspect or how long the station has operated > from the building. The owner of the warehouse had no idea the building was > being used as an illegal station, authorities said. > > With its flat terrain, South Florida has long been described as the pirate > radio capital of the United States. > > On any given day, between nine and 20 illegal stations are playing in South > Florida, according to the Florida Association of Broadcasters. Some air > around the clock; many switch frequencies and locations often. > > ''They get a kick out of it. They laugh at everybody,'' said C. Patrick > Roberts, the organization's president. > > With readily available technology and radio mega-companies that critics say > have limited playlists, unlicensed radio stations have proliferated in > recent years. > > Supporters contend the stations provide niche programming -- often geared > toward ethnic groups -- not found on overcommercialized radio stations. > > The FAA says it has launched 30 similar investigations into pirate stations > interfering with airport transmissions during the past decade. They now > have more help from the state. > > A Florida anti-piracy law went into effect last summer, making interfering > with signals from licensed public or commercial stations, or broadcasting > without a license, a third-degree felony. > > That gave FDLE the power to aggressively go after pirate radio stations. > Since then, agents have shut down about five illegal radio stations. > > So far, they have arrested at least two men in South Florida. > > Last year, agents shut down Vibez, a popular Caribbean station that had > operated quite openly. > Article: 222486 of rec.radio.amateur.antenna From: "Bill Turner" Subject: Re: antenna theory for idiots? References: Message-ID: <441d9ee8_5@newsfeed.slurp.net> Date: 19 Mar 2006 13:11:52 -0500 ORIGINAL MESSAGE: Lisa Simpson wrote: > Can anyone point me at a good book or website that can teach me about > antenna theory from a beginner's standpoint? I'm getting into SWL & > feel I really need to understand this subject well . . . *********** REPLY SEPARATOR *********** The ARRL Antenna Handbook starts at the very beginning and goes as far as you would like for ham radio designs. If you become so enthralled with antennas that you want to go into it professionally, there are other books but for us hams. that one will do. Bill, W6WRT Article: 222487 of rec.radio.amateur.antenna From: Bob Miller Subject: Re: antenna theory for idiots? Message-ID: References: Date: Sun, 19 Mar 2006 19:07:18 GMT On Sun, 19 Mar 2006 02:23:07 GMT, "Lisa Simpson" wrote: >Can anyone point me at a good book or website that can teach me about >antenna theory from a beginner's standpoint? I'm getting into SWL & feel I >really need to understand this subject well . . . > Better Shortwave Reception, by William Orr, out of print, but a used copy is at: http://www.alibris.com/search/search.cfm?S=R&wauth=William+I.+Orr&siteID=WfbLd2hpy3I-B7MHZRtvMDVKJzo0z0Tvng Mr. Orr was one of the more understandable writers on things electronic... bob k5qwg Article: 222488 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <28826-441C4099-1651@storefull-3255.bay.webtv.net> <121ojih732ucf6f@corp.supernews.com> <%Y3Tf.584343$qk4.104946@bgtnsc05-news.ops.worldnet.att.net> <121pmm3758jm4f4@corp.supernews.com> Message-ID: <3tiTf.45184$2O6.38537@newssvr12.news.prodigy.com> Date: Sun, 19 Mar 2006 19:40:47 GMT Roy Lewallen wrote: > -- we get > exactly the same result either way because superposition holds. Thinking that the result is the same and that nothing gets lost during superpositon is a misconception. Consider the following. PSK modem A--------------------------------------PSK modem B When a single signal flows from A to B, perfect information transfer occurs. When a single signal flows from B to A, perfect information transfer occurs. Now superpose the two information streams. ZERO information transfer occurs. Superposition is not magic and the result is not the same. The superposition of forward and reflected currents cause 100% loss of phase information in the standing wave current phase measurement. It is analogous to the problem above. A standing wave current cannot be used to determine the delay through a coil. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222489 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Current through coils Message-ID: References: <%Y3Tf.584343$qk4.104946@bgtnsc05-news.ops.worldnet.att.net> <121pmm3758jm4f4@corp.supernews.com> <8kqp12h5hs3bmrn2vn34i96m5fr0osv90s@4ax.com> Date: Sun, 19 Mar 2006 19:53:38 GMT On Sun, 19 Mar 2006 12:41:43 GMT, Cecil Moore wrote: >Owen Duffy wrote: > >> Cecil Moore wrote: >>>Please see http://www.qsl.net/w5dxp/current.htm >> >> I refer to the diagram in the section entitled "What EZNEC Says About >> Current Distribution Using Inductive Loading Stubs" >> >> You use the diagram to assert that there is "not a lot of difference >> between inductive loading stubs and loading coils" by comparing the >> current distribution with another case. >> >> You show graphically the current on each side of the stub. You do not >> show the current in each wire of the stub or the sum of the currents >> in the stub. > >The currents in stubs cannot be displayed very well at full size in >EZNEC just as the currents in coils cannot be displayed very well. >Maybe an enlarged view would show it. I will try to do that. Or even words that explain that the diagram is incomplete, that there are currents flowing in the stub wires, and that they don't balance each other so they participate in the antenna's total current moment. The currents in the stubs is an explanation for the difference in the currents in the main radiator at each side of the stub connection. Is it fair to say that though the diagram may resemble the first diagram on the page, to some extent, the reason they are similar is that the second one is incomplete. > >> EZNEC calculates the currents in each wire of the stub? Aren't those >> currents a relevant detail that you have omitted from the diagram. > >Remember the present discussion is about the ability to use standing >wave current phase to measure the electrical length of a wire or a >coil. I have run the currents that you mention. The phase of the current >is almost constant through the stubs. The phase of the current is >almost constant through the coils. Would you like to see a list >of the current at points through the stub Vs the current at points >through the coil? No thanks, I didn't ask the question without creating a model and inspecting the currents. The phase of the currents is only one dimension. Though the phase of the current in adjacent segments in all wires (including the stubs) is commonly similar (except where a phase reversal occurs), in general, the magnitude and phase of paired stub segments that effectively form a transmission line section are not equal in magnitude and phase. My point is really about whether the subject diagram supports your argument, especially if it is incomplete and if it misrepresents the scenario. Owen -- Article: 222490 of rec.radio.amateur.antenna From: ml Subject: vert vs dipole gut comparison Message-ID: Date: Sun, 19 Mar 2006 20:07:05 GMT hi i am pondering this again after thinking the odds of being about to put a beam up are slim currently i have a nice dipole CF horiz via a topside sgc , i am happy w/it i think i might be able to get a verticle (all bander) up there but then i wonder overall if it would really pay from just a performance point of view the reviews i see i personally average as some signals would prob come in bettter on one and some signals the other 'depending' but i guess i can't quantify if at the end of the day i'd say wow really glad i had that vert or if perhaps having a 2nd antenna would really net me only a marginal end of year bunch of extra qso's perhaps a unrelated question #2 given the building master tv antenna is close by, would one guess that a verticle or a small triband beam would give off more tvi?? assume both would be slightly higher than the tv ant but close proximity thanks Article: 222491 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <121mh75g3ekkme9@corp.supernews.com> <28826-441C4099-1651@storefull-3255.bay.webtv.net> <121ojih732ucf6f@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> Subject: Re: Current through coils Message-ID: Date: Sun, 19 Mar 2006 15:39:23 -0500 wrote > This long painful thread (it's been going on years now) started because > K3BU claimed a loading inductor had most of the current in the first > few turns. I am back after loooong absence here and see more misinformation coming from Tom, W8JI. I claimed that current in the antenna coil is NOT CONSTANT (or near) as he claimed. The case was of electrical quarter wave vertical radiator (as loaded mobile antenna) and that the current is distributed, varying across the coil as I have experienced, W9UCW has measured and Cecil has explained. The refresher is at http://www.k3bu.us/loadingcoils.htm The thread is "painful" because some people try to subvert the reality and keep clinging to wrong "reality" and some try to set the record straight.. This misinformation keeps being perpetuated in literature and it even crept into the latest ON4UN 4th edition of Low Band DXing (see page 9-33). The significance of properly realizing the current distribution in the loading coil is in how the modeling programs treat the phenomena and major screw-up will show up in multi element loaded antenna systems, where error will multiply and give false results. There are few more statements slightly out of true on W8JI pages, but would have to be left for later time. I apologize for being away from this NG, my AOL provider dumped NG and I am slowly dumping AOL and will migrate to optonline.net and back to NG. Also business and other QRM keeps me away, but I hope is that "tings" will improve. 73 to all Yuri, K3BU www.K3BU.us www.TeslaRadio.org Article: 222492 of rec.radio.amateur.antenna From: "Bill Turner" Subject: Re: vert vs dipole gut comparison References: Message-ID: <441dcd21_4@newsfeed.slurp.net> Date: 19 Mar 2006 16:29:05 -0500 ORIGINAL MESSAGE: ml wrote: > the reviews i see i personally average as some signals would prob > come in bettter on one and some signals the other 'depending' > > but i guess i can't quantify if at the end of the day i'd say wow > really glad i had that vert or if perhaps having a 2nd antenna > would really net me only a marginal end of year bunch of extra qso's *********** REPLY SEPARATOR *********** For a couple of years I had a 40 meter half-wave dipole and a 40 meter ground plane with elevated radials. Both were at about the same height and had full size elements (no loading coils). I'd say about 95% of the time the performance was nearly identical between the two, but there were times when one would outperform the other, but not by much. If you are in an environment with high man made noise, you will find the horizontal dipole is quieter, but otherwise I would just put up which ever is easier mechanically, or ideally, put up both. Bill, W6WRT Article: 222493 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <28826-441C4099-1651@storefull-3255.bay.webtv.net> <121ojih732ucf6f@corp.supernews.com> <%Y3Tf.584343$qk4.104946@bgtnsc05-news.ops.worldnet.att.net> <121pmm3758jm4f4@corp.supernews.com> <3tiTf.45184$2O6.38537@newssvr12.news.prodigy.com> Message-ID: <9hkTf.48560$F_3.36297@newssvr29.news.prodigy.net> Date: Sun, 19 Mar 2006 21:44:37 GMT Cecil Moore wrote: > Roy Lewallen wrote: > >> -- we get exactly the same result either way because superposition >> holds. > > > Thinking that the result is the same and that nothing gets > lost during superpositon is a misconception. Consider the > following. > > PSK modem A--------------------------------------PSK modem B > > When a single signal flows from A to B, perfect information > transfer occurs. When a single signal flows from B to A, > perfect information transfer occurs. Now superpose the > two information streams. ZERO information transfer occurs. > Superposition is not magic and the result is not the same. > > The superposition of forward and reflected currents cause > 100% loss of phase information in the standing wave current > phase measurement. It is analogous to the problem above. > > A standing wave current cannot be used to determine the > delay through a coil. Cecil, that's the worst analogy I've ever read in my life. 73, Tom Donaly, KA6RUH Article: 222494 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: antenna theory for idiots? Date: Sun, 19 Mar 2006 16:12:30 -0600 Message-ID: <28826-441DD74E-1848@storefull-3255.bay.webtv.net> References: Bob Miller wrote: "Can anyone point me at a dood book or website that can teach me about antenna theory from a beginner`s viewpoint?" The ARRL 2006 Handbook devotes Chapter 22 to that task and provides a good bibliography at the end of the chapter for further study. Best regards, Richard Harrison, KB5WZI Article: 222495 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <%Y3Tf.584343$qk4.104946@bgtnsc05-news.ops.worldnet.att.net> <121pmm3758jm4f4@corp.supernews.com> <8kqp12h5hs3bmrn2vn34i96m5fr0osv90s@4ax.com> Message-ID: Date: Sun, 19 Mar 2006 22:58:53 GMT Owen Duffy wrote: > The currents in the stubs is an explanation for the difference in the > currents in the main radiator at each side of the stub connection. Just as are the currents in the coils. > Is it fair to say that though the diagram may resemble the first > diagram on the page, to some extent, the reason they are similar is > that the second one is incomplete. I sent you a .gif file giving you the full perspective. > My point is really about whether the subject diagram supports your > argument, especially if it is incomplete and if it misrepresents the > scenario. The phase shift through the stub is the same as through the coil is the same as through the wire. It is simply zero according to the standing wave current phase which is incapable of measuring phase. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222496 of rec.radio.amateur.antenna From: "Old Ed" References: Subject: Re: First Attempt Message-ID: Date: Sun, 19 Mar 2006 23:06:59 GMT Reg, The type of antenna you describe is very useful and popular. However, your assertion is much too sweeping as a generalization. In no particular order, here are some caveats: 1. The qualifier "best" is largely meaningless, absent an agreed set of weighted criteria for "goodness." (How important is: size? weight? cost? visual profile? bandwidth? instant QSY? gain? pattern? low-band performance vs. high-band performance? power-handling capacity? need for tuner? etc., etc., etc.) 2. A good case can be made that choosing the "right" length is "better" than a random length, within this type. 3. An excellent case can be made that center-fed is NOT always the "best" option, within this type. 4. I'll let the fans of this antenna type chime in with why they prefer balanced tuners and/or tuned feeders to the use of an unbalanced tuner... if they want to. (I use more tailored antennas, and don't need a tuner of any kind, most of the time.) 73, Ed "Reg Edwards" wrote in message news:dvhp20$ap9$1@nwrdmz01.dmz.ncs.ea.ibs-infra.bt.com... > The best, all round, all band, antenna is a high centre-fed dipole of > no particular length, fed with an open-wire feedline of no particular > length or impedance, all the way to the shack, used with a choke-balun > and an unbalanced tuner. > > It is good down to the frequency at which the dipole is about > 1/3-wavelength long. > > Simplicity = efficiency. > > Once tried you will never return to anything else. > ---- > Reg. > > Article: 222497 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <28826-441C4099-1651@storefull-3255.bay.webtv.net> <121ojih732ucf6f@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> Message-ID: Date: Sun, 19 Mar 2006 23:14:38 GMT Yuri Blanarovich wrote: > I claimed that current in the antenna coil is NOT CONSTANT (or near) as he > claimed. Only one out of a dozen tests run by W8JI and W7EL showed the currents to be equal. All the other tests showed the currents to be *unequal*. > The significance of properly realizing the current distribution in the > loading coil is in how the modeling programs treat the phenomena and major > screw-up will show up in multi element loaded antenna systems, where error > will multiply and give false results. The helix option in EZNEC supports the notion that the currents are hardly ever equal. If a coil is installed at a standing wave current maximum or minimum the currents can be equal. If the coil is installed at a point where the slope of the current is maximum, the difference in the currents at each end will be maximum. That's pretty simple physics. The currents at each end of a coil in a standing wave environment depends upon where it is installed. I provided an example where the current "into" the bottom of the coil was 0.17 amps and the current "out of" the top of the coil was 2.0 amps. W8JI said the lumped-circuit inductance could explain that so I asked him to explain it to all of us. So far, no response. Wonder how a model that assumes faster than light propagation of waves and absolutely equal current magnitude and phase is going to explain a 1.8 amp difference and a phase shift of 180 degrees? -- 73, Cecil http://www.qsl.net/w5dxp Article: 222498 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <28826-441C4099-1651@storefull-3255.bay.webtv.net> <121ojih732ucf6f@corp.supernews.com> <%Y3Tf.584343$qk4.104946@bgtnsc05-news.ops.worldnet.att.net> <121pmm3758jm4f4@corp.supernews.com> <3tiTf.45184$2O6.38537@newssvr12.news.prodigy.com> <9hkTf.48560$F_3.36297@newssvr29.news.prodigy.net> Message-ID: Date: Sun, 19 Mar 2006 23:21:04 GMT Tom Donaly wrote: > Cecil, that's the worst analogy I've ever read in my > life. The PSK signals lose phase when they are superposed. The forward and reflected currents lose phase when they are superposed. Looks like a perfect analogy to me. Do you disagree with Gene Fuller? > Gene Fuller, W4SZ wrote: >> In a standing wave antenna problem, such as the one you describe, there is no >> remaining phase information. Any specific phase characteristics of the traveling >> waves died out when the startup transients died out. >> >> Phase is gone. Kaput. Vanished. Cannot be recovered. Never to be seen again. >> >> The only "phase" remaining is the cos (kz) term, which is really an amplitude >> description, not a phase. Do you disagree with Gene? How can Tom and Roy possibly use a signal whose phase cannot be recovered to measure phase? -- 73, Cecil http://www.qsl.net/w5dxp Article: 222499 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <28826-441C4099-1651@storefull-3255.bay.webtv.net> <121ojih732ucf6f@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> Message-ID: Date: Sun, 19 Mar 2006 23:36:46 GMT w8ji@akorn.net wrote: > The loading coil, if well-designed and of compact size, doesn't have to > have any significant current taper. The current taper depends upon where the coil is installed in the standing wave environment. There is no doubt that the coil distorts the current away from the ideal thin-wire dipole case. But that coil does have to have a significant delay, in the tens of degrees according to Dr. Corum. Since you and Roy mistakenly used standing wave current phase to try to measure the delay through a coil, the following posting resulted: > Gene Fuller, W4SZ wrote: >> In a standing wave antenna problem, such as the one you describe, there is no >> remaining phase information. Any specific phase characteristics of the traveling >> waves died out when the startup transients died out. >> >> Phase is gone. Kaput. Vanished. Cannot be recovered. Never to be seen again. >> >> The only "phase" remaining is the cos (kz) term, which is really an amplitude >> description, not a phase. Gene is 100% correct and we all should be grateful for that posting. Neither you nor Roy have ever made a valid measurement of the delay through a coil. It is admittedly a difficult measurement to make directly. Ramo and Whinnery say it "is usually of prohibitive difficulty". -- 73, Cecil http://www.qsl.net/w5dxp Article: 222500 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Current through coils References: <%Y3Tf.584343$qk4.104946@bgtnsc05-news.ops.worldnet.att.net> <121pmm3758jm4f4@corp.supernews.com> <8kqp12h5hs3bmrn2vn34i96m5fr0osv90s@4ax.com> Message-ID: Date: Sun, 19 Mar 2006 23:49:54 GMT Cecil Moore wrote: > Owen Duffy wrote: > >> The currents in the stubs is an explanation for the difference in the >> currents in the main radiator at each side of the stub connection. > > > Just as are the currents in the coils. > >> Is it fair to say that though the diagram may resemble the first >> diagram on the page, to some extent, the reason they are similar is >> that the second one is incomplete. > > > I sent you a .gif file giving you the full perspective. > >> My point is really about whether the subject diagram supports your >> argument, especially if it is incomplete and if it misrepresents the >> scenario. > > > The phase shift through the stub is the same as through the coil is > the same as through the wire. It is simply zero according to the > standing wave current phase which is incapable of measuring phase. For anyone who is foolish enough to believe Cecil when he says that all phase information is lost when two oppositely traveling waves create a standing wave, consider the following, adapted from Georg Joos book _Theoretical Physics_: consider two traveling waves going in opposite directions represented mathematically by Ae^i(wt-kx) + Ae^i(wt+kx+d) where A is the same amplitude for both waves, i is the square root of -1, k is 2*pi/wavelength, w is the radian frequency, t is time, x is distance, and d is the phase difference between the two waves. This is just another way of writing 2Acos(kx+d/2)(e^i(wt+d/2). Notice that the part cos(kx+d/2) still contains the phase information? If Cecil were any kind of experimentalist he could easily tease the phase information out of any standing wave on his antenna system. 73, Tom Donaly, KA6RUH Article: 222501 of rec.radio.amateur.antenna From: "John, N9JG" References: Subject: Re: aluminium element segment corrosion & weather proofing... ? Message-ID: Date: Mon, 20 Mar 2006 00:31:05 GMT Another product that works very well is Lawson 59933 Copper Anti-Seize Anti-Corrosion Compound http://webapp.lawsonproducts.com/website/showItem?itemNum=59933 This is the same product that comes with a Butternut vertical antenna. It consists of a synthetic grease base, copper, thickener, and rust inhibitor. It can withstand temperature ranges from -65°F to 1800°F, which should be adequate for most ham applications. John, N9JG "KenW" wrote in message news:b8po12lhi8i7huql2f4cjbnof1ue6uqvj0@4ax.com... > On Sat, 18 Mar 2006 19:16:51 GMT, Cecil Moore > wrote: > >>Kba wrote: >>> just have some plans for yagi construction, but yagi tapering >>> segments may need some corrosion & weather protection... >>> Any recommendations ? >>> Aluminum powder or grease ? or without ?? >> >>There's a conductive compound that reduces oxidation. It's >>sold under various brand names. Oxiguard comes to mind >>but that may be a toothpaste compound or some such. :-) > > Besides compound in the joints I have always used Krylon clear spray > paint. Antennas look like new for a few years. Article: 222502 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <28826-441C4099-1651@storefull-3255.bay.webtv.net> <121ojih732ucf6f@corp.supernews.com> <%Y3Tf.584343$qk4.104946@bgtnsc05-news.ops.worldnet.att.net> <121pmm3758jm4f4@corp.supernews.com> <3tiTf.45184$2O6.38537@newssvr12.news.prodigy.com> <9hkTf.48560$F_3.36297@newssvr29.news.prodigy.net> Message-ID: Date: Mon, 20 Mar 2006 00:30:27 GMT Cecil Moore wrote: > Tom Donaly wrote: > >> Cecil, that's the worst analogy I've ever read in my >> life. > > > The PSK signals lose phase when they are superposed. The forward > and reflected currents lose phase when they are superposed. Looks > like a perfect analogy to me. Do you disagree with Gene Fuller? > >> Gene Fuller, W4SZ wrote: >> >>> In a standing wave antenna problem, such as the one you describe, >>> there is no remaining phase information. Any specific phase >>> characteristics of the traveling waves died out when the startup >>> transients died out. >>> >>> Phase is gone. Kaput. Vanished. Cannot be recovered. Never to be seen >>> again. >>> >>> The only "phase" remaining is the cos (kz) term, which is really an >>> amplitude description, not a phase. > > > Do you disagree with Gene? How can Tom and Roy possibly use a signal > whose phase cannot be recovered to measure phase? But Cecil, it can be recovered. See my earlier remarks. 73, Tom Donaly, KA6RUH Article: 222503 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <28826-441C4099-1651@storefull-3255.bay.webtv.net> <121ojih732ucf6f@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> Message-ID: Date: Mon, 20 Mar 2006 00:35:53 GMT Cecil Moore wrote: > w8ji@akorn.net wrote: > >> The loading coil, if well-designed and of compact size, doesn't have to >> have any significant current taper. > > > The current taper depends upon where the coil is installed in > the standing wave environment. There is no doubt that the coil > distorts the current away from the ideal thin-wire dipole case. > But that coil does have to have a significant delay, in the tens > of degrees according to Dr. Corum. Since you and Roy mistakenly > used standing wave current phase to try to measure the delay > through a coil, the following posting resulted: > >> Gene Fuller, W4SZ wrote: >> >>> In a standing wave antenna problem, such as the one you describe, >>> there is no remaining phase information. Any specific phase >>> characteristics of the traveling waves died out when the startup >>> transients died out. >>> >>> Phase is gone. Kaput. Vanished. Cannot be recovered. Never to be seen >>> again. >>> >>> The only "phase" remaining is the cos (kz) term, which is really an >>> amplitude description, not a phase. > > > Gene is 100% correct and we all should be grateful for that posting. > > Neither you nor Roy have ever made a valid measurement of the > delay through a coil. It is admittedly a difficult measurement > to make directly. Ramo and Whinnery say it "is usually of > prohibitive difficulty". I think that if Gene believes that, he should redo his math. 73, Tom Donaly, KA6RUH Article: 222504 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <121ojih732ucf6f@corp.supernews.com> <%Y3Tf.584343$qk4.104946@bgtnsc05-news.ops.worldnet.att.net> <121pmm3758jm4f4@corp.supernews.com> <8kqp12h5hs3bmrn2vn34i96m5fr0osv90s@4ax.com> <121q4fbgb89gb1a@corp.supernews.com> <121qh4dm7om8j13@corp.supernews.com> <1142813624.391779.279150@t31g2000cwb.googlegroups.com> <1142814316.040782.285000@i39g2000cwa.googlegroups.com> Subject: Re: Current through coils Message-ID: Date: Sun, 19 Mar 2006 19:56:51 -0500 > > I've been trying to tell Yuri (and others) that for three years now. > > > 73 Tom > Tom. You tell that to the RF ammeters installed on the vertical, W9UCW's pictures on my page! You can mumbo-jumbo all the theory, you can dream of, but reality shows that in the say, quarter wave vertical, with loading coil the current at both ends of the coil is different. Cecil explained the various situation depending where the coil is placed within the radiator and at overall antenna curve. Try this test, no meters necessary (perhaps the aquarium strip thermometer): Take your 80m Hustler antenna with Hustler loading coil and whip. At the resonant frequency put about 600 Watts to it for a while. Stop transmitting and go feel (or read the temperature on the strips) the coil, bottom end and the top end. Same temperature? Temperature is proportional to the current flow (same diameter wire) - warmer end - more current. Then test two: Keep the RF flowing until heat shrink tubing on the coil starts melting. Where does it melt first? Bottom of the coil or nicely uniformly as you claim it should? Then answer Cecil question about his demonstration of different currents at the ends! The rest is on my web page as I mentioned, with pictures. 73 Yuri, www.K3BU.us Article: 222505 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Current through coils Date: Sun, 19 Mar 2006 18:08:03 -0800 Message-ID: <121s3k66tfvcq9d@corp.supernews.com> References: <121ojih732ucf6f@corp.supernews.com> <%Y3Tf.584343$qk4.104946@bgtnsc05-news.ops.worldnet.att.net> <121pmm3758jm4f4@corp.supernews.com> <8kqp12h5hs3bmrn2vn34i96m5fr0osv90s@4ax.com> <121q4fbgb89gb1a@corp.supernews.com> <121qh4dm7om8j13@corp.supernews.com> <1142813624.391779.279150@t31g2000cwb.googlegroups.com> K7ITM wrote: > Roy wrote, "... That is, the coil is capacitively coupled to ground, > and this > causes displacement current from the coil to ground." > > In fact, if there were no such current -- if there were no capacitance > from the coil to the world outside the coil -- then the time delay > through the coil, calculated from tau = sqrt(L*C), would be zero. It > is exactly this current that allows there to be a transmission-line > behaviour and a corresponding time delay. Yes. And this, not the C across the coil, is what should be used for transmission line formulas when treating an inductor as a transmission line. When the ground was removed and replaced by a wire, the transmission line properties of the coil changed dramatically, while the C across the coil didn't change significantly. > That's not to say, however, that a physically very small loading coil > with practically no capacitance to ground would not work as a loading > coil. It just wouldn't have a transmission line behaviour worth > mentioning. > > It is also exactly this displacement current from a large coil that > allows the current at one end of the coil to be substantially different > from the current at the other end. Yes again, with one slight modification. You'll note from the EZNEC models that the current actually increases some as you go up from the bottom of the inductor. This is the effect noted by King which is due to imperfect coupling between turns. It results in currents at both ends being less than at the center. A transmission line can be represented by a series of L networks with series L and shunt C. You can achieve any desired accuracy by breaking the total L and C into enough L network sections. The requirement for validity is that the length of line represented by each section must be very small relative to a wavelength. For the example coil, a single section is entirely adequate at the 5.89 MHz frequency of analysis. However, at some higher frequency this model won't be adequate, and either more L sections or a distributed model is necessary. If the reasons for this aren't obvious, many texts cover it quite well. No special "traveling wave" analysis is required. I spent several years of my career designing very high speed TDR and sampling circuits, which involved a great deal of modeling. At the tens of GHz equivalent bandwidths of the circuitry, even very small structures such as chip capacitors and short connecting runs often had to be treated as transmission lines. One of the skills important to building an accurate model which would run in a reasonable amount of time, particularly on the much slower machines being used in the earlier part of that period, is determining when a lumped L, pi, or tee model is adequate and when a full-blown transmission line model has to be used(*). My models were used in the development of quite a number of circuits that were successfully produced in large numbers. (*) One of the characteristics of the SPICE programs at the time was that the time step was never longer than the delay of the shortest transmission line in the model. So if you willy-nilly modeled everything as a transmission line, you'd end up with an excruciatingly short time step and consequently unnecessarily long calculation time. Roy Lewallen, W7EL Article: 222506 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <121ojih732ucf6f@corp.supernews.com> <%Y3Tf.584343$qk4.104946@bgtnsc05-news.ops.worldnet.att.net> <121pmm3758jm4f4@corp.supernews.com> <8kqp12h5hs3bmrn2vn34i96m5fr0osv90s@4ax.com> <121q4fbgb89gb1a@corp.supernews.com> <121qh4dm7om8j13@corp.supernews.com> <1142813624.391779.279150@t31g2000cwb.googlegroups.com> <1142814316.040782.285000@i39g2000cwa.googlegroups.com> <1142822862.985006.247970@t31g2000cwb.googlegroups.com> Subject: Re: Current through coils Message-ID: <2upTf.185$wg6.164@fe10.lga> Date: Sun, 19 Mar 2006 22:39:33 -0500 wrote in message news:1142822862.985006.247970@t31g2000cwb.googlegroups.com... > > Yuri Blanarovich wrote: > >> Tom. >> You tell that to the RF ammeters installed on the vertical, W9UCW's >> pictures >> on my page! > > 1.) I can build an antenna that has greatly uneven currents at the ends > of the loading coil, but the antenna rea above the inductor is wasted > and the system will be less efficient than a properly designed system. > > 2.) The meters are large and have a good deal of self-capacitance > compared to the capacitance at the point where they are connected, and > are directly connected to the antenna. Bad idea to base a whole concept > of how an antenna works on something like that. > >> You can mumbo-jumbo all the theory, you can dream of, but reality shows >> that >> in the say, quarter wave vertical, with loading coil the current at both >> ends of the coil is different. > > It can be different, but in a well designed system it is essentially > the same. The only difference is caused by displacement currents, and > that is a result of stray capacitance. Wind a good coil that has low > self-C to the outside world compared to the antenna hanging above the > coil, and the problem of large uneven current goes away. > >>Cecil explained the various situation >> depending where the coil is placed within the radiator and at overall >> antenna curve. > > I doubt that. If he explained it in those terms he was missing some > important points. > >> Try this test, no meters necessary (perhaps the aquarium strip >> thermometer): >> Take your 80m Hustler antenna with Hustler loading coil and whip. At the >> resonant frequency put about 600 Watts to it for a while. Stop >> transmitting >> and go feel (or read the temperature on the strips) the coil, bottom end >> and >> the top end. Same temperature? Temperature is proportional to the current >> flow (same diameter wire) - warmer end - more current. > > Are you saying thermal effects have no bearing? > > It's getting pretty dangerous to write a theory based only on a Hustler > mobile coil with almost no stinger above the coil. One of the reasons > the Hustler works so poorly is the distributed capacitance in the coil > is large compared to the tiny stinger above the coil. > > The Hustler has narrow bandwidth and poor efficiency because of the > coil design. > >> Then test two: Keep the RF flowing until heat shrink tubing on the coil >> starts melting. Where does it melt first? Bottom of the coil or nicely >> uniformly as you claim it should? > > I never claimed uniformly in ALL coils. I set boundaries as to the > conditions. I can replace that Hustler coil with another coil and ruin > your theory about standing waves and missing antenna degrees. > > 73 Tom > Yea Tom, it all started with ALL coils, it is MY theory and you can ruin MY theory. Riiiight! It's getting pathetic. Yea, meters are too big, Hustler is crapy, Cecil is wrong, and you never claimed uniformly in all coils, just those that you have. Reality is wrong, your "theory" is right! Rrrrright!!! But what a coincidence that what W9UCW measured, jives with what Cecil calculated. Hmmm! ANSWER Cecil's question about his modeled example. I guess when someone is stuck on something and dunt gitit, its tough! I am just waiting how you will come around, dancing around in mumbo-jumbo circles and then will become guru on how current IS different in the loading coils. Happened in the past, will happen again. You are WRONG, reality proves it, regardless of your detours. BTW, what engineering degree, from what university do you have or PE that gives you right to put labels like "JI Engineering" on your products? bada BUm Article: 222507 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: vert vs dipole gut comparison Message-ID: <80bs125aalppg522mun6hr442egt3bk97i@4ax.com> References: Date: Mon, 20 Mar 2006 04:18:26 GMT On Sun, 19 Mar 2006 22:15:00 -0500, Mike Coslo wrote: > Some times the vertical works better, and sometimes the horizontal >works better. I'm having a heck of a time correlating exactly *why and Mike, we need a clear definition of the meaning of "works" in your data gathering and analysis. Owen -- Article: 222508 of rec.radio.amateur.antenna Subject: Ink From: mshawjr@frontiernet.net Message-ID: Date: Mon, 20 Mar 2006 04:23:01 GMT Man I have found this site that has the cheapest ink for any printer. You can compare prices and then review the companies on service and quality. Let me know what you think Article: 222509 of rec.radio.amateur.antenna From: "Dave Turner" References: Subject: Re: Ink Date: Mon, 20 Mar 2006 12:27:48 +0800 Message-ID: <441e2f14@quokka.wn.com.au> > whois imagraphix.com Registrant: Murphey Shaw 12 Blackwatch Trail Fairport, NY 14450 , United States Registered through: GoDaddy.com Domain Name: IMAGRAPHIX.COM Created on: 09-Dec-04 Expires on: 09-Dec-07 Last Updated on: 14-Feb-06 Administrative Contact: Shaw, Murphey mshawjr@frontiernet.net 12 Blackwatch Trail Fairport, NY 14450 , United States 5854148735 Technical Contact: DNS, Administrator administrator@siteprotect.com 1 N State Street 12th Floor Chicago, IL 60602 , United States +1.3122362132 Fax -- +1.3122361958 Domain servers in listed order: NS3.SECURESERVER.NET NS4.SECURESERVER.NET Article: 222510 of rec.radio.amateur.antenna From: "Ken Bessler" Subject: Looking for the right connector Message-ID: <3DqTf.62056$Dh.37069@dukeread04> Date: Sun, 19 Mar 2006 22:57:32 -0600 I'm installing 802.11b/g in my IBM ThinkPad T23. I've done quite a bit of research and got a 250mw WiFi internal (mini PCI) card, 2 micro coax (1.37mm OD) antenna leads and I'm building two antennas but I'm stumped on how to connect the antennas to the laptop. Ideally the connectors should be inline, like a headphone extension cable. The connectors will be secured to the rear of the LCD display in a way so that they point up when the display is open yet the antennas can be removed when I close the screen. Should I just use the 2 leftover Elecraft BNC chassis mounts I have? Anyone have a better (smaller) choice? What about RCA or 3/32" headphone plugs? Would they present too much of an impedance bump at 5.1ghz? -- 73's de Ken KG0WX - Kadiddlehopper #11808, Flying Pigs #-1055, Grid EM17io, Elecraft K2 #4913, XG2, 4SQRP Tenna Dipper, Heath GD-1B, MP-1(X) antenna & HLA-150 amplifier. Article: 222511 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: Looking for the right connector References: <3DqTf.62056$Dh.37069@dukeread04> Message-ID: <75r1f3-d8m.ln1@p400bob.personal.cox.net> Date: Sun, 19 Mar 2006 23:28:39 -0600 Hi Ken Yes stay away from RCA and headphone plugs, for exactly the reason you mentioned. I'd recommend SMA plugs and sockets, They are in pretty standard use up to about 12GHz. Make sure you terminate them properly or have some cables made up. I'd also be careful using that thin coax over any kind of distance. The losses will really mount up! Cheers Bob Ken Bessler wrote: > I'm installing 802.11b/g in my IBM ThinkPad T23. Article: 222512 of rec.radio.amateur.antenna From: Butch Magee Subject: Re: OLD 5 BAND TRP ANTENNA Date: Mon, 20 Mar 2006 00:17:37 -0600 Message-ID: <121si85t70k5sd6@corp.supernews.com> References: <441c880a$0$7604$afc38c87@news.optusnet.com.au> Richard Miller wrote: > Hi > > I was just digging around the garage and I found my old multi band trap > vertical antenna LOL.. Anyway it covered 80m to 10m and I got it from Dick > Smith back in the 80's that's a long time ago.. Dos anyone have a diagram > for one of them I can not find mine but still looking for it.. Can any one > help.. > > > > > > > > 73's Regards, > > Richard Miller > E-mail: wizzard6@optusnet.com.au > > > Check out DXEngineering and see if by chance they have the parts you need. They carry several different model lparts and mods (I think mods). Bunch of good guys there for sure. 73, Butch KF5DE Article: 222513 of rec.radio.amateur.antenna From: "Ken Bessler" References: <3DqTf.62056$Dh.37069@dukeread04> <75r1f3-d8m.ln1@p400bob.personal.cox.net> Subject: Re: Looking for the right connector Message-ID: Date: Mon, 20 Mar 2006 00:20:11 -0600 "Bob Bob" wrote in message news:75r1f3-d8m.ln1@p400bob.personal.cox.net... > Hi Ken > > Yes stay away from RCA and headphone plugs, for exactly the reason you > mentioned. > > I'd recommend SMA plugs and sockets, They are in pretty standard use up > to about 12GHz. Make sure you terminate them properly or have some > cables made up. > > I'd also be careful using that thin coax over any kind of distance. The > losses will really mount up! > > Cheers Bob Thanks for the tips, Bob. I was worried about losses but I downloaded the factory data sheet for this coax - for a 500mm run, I'm looking at a loss of 0.94db @ 2.4ghz and 1.53db @ 5.1ghz. I tried finding the internal connector (U.FL type) but gave up when I saw DigiKey selling a 1000mm cable with U.FL connectors installed on both ends. I cut the cable in half. The cable looks like good stuff - VERY tiny but well built. $10.... I'll look into SMA connectors - does anyone know if they make a push on variant? Ken KG0WX Article: 222514 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Looking for the right connector Date: Sun, 19 Mar 2006 22:26:47 -0800 Message-ID: <121sip9rvkvq94a@corp.supernews.com> References: <3DqTf.62056$Dh.37069@dukeread04> <75r1f3-d8m.ln1@p400bob.personal.cox.net> Ken Bessler wrote: > . . . > I'll look into SMA connectors - does anyone know if they make a push on > variant? SMB is probably what you want. Roy Lewallen, W7EL Article: 222515 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Current through coils Date: Sun, 19 Mar 2006 23:23:54 -0800 Message-ID: <121sm4codnhupa5@corp.supernews.com> References: <121ojih732ucf6f@corp.supernews.com> <%Y3Tf.584343$qk4.104946@bgtnsc05-news.ops.worldnet.att.net> <121pmm3758jm4f4@corp.supernews.com> <8kqp12h5hs3bmrn2vn34i96m5fr0osv90s@4ax.com> <121q4fbgb89gb1a@corp.supernews.com> <121qh4dm7om8j13@corp.supernews.com> <1142813624.391779.279150@t31g2000cwb.googlegroups.com> <121s3k66tfvcq9d@corp.supernews.com> Correction: Roy Lewallen wrote: > K7ITM wrote: >> . . . >> It is also exactly this displacement current from a large coil that >> allows the current at one end of the coil to be substantially different >> from the current at the other end. [I wrote:] > Yes again, with one slight modification. You'll note from the EZNEC > models that the current actually increases some as you go up from the > bottom of the inductor. This is the effect noted by King which is due to > imperfect coupling between turns. It results in currents at both ends > being less than at the center. Tom's statement doesn't need modification, it's correct as written. Imperfect coupling between turns causes current which is different at the ends than in the middle. Tom said, correctly, that displacement current is the cause of the currents at the ends being different from each other. Roy Lewallen, W7EL Article: 222516 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Current through coils Date: Mon, 20 Mar 2006 03:14:58 -0600 Message-ID: <2813-441E7292-2246@storefull-3257.bay.webtv.net> References: <1141772023.638201.196770@j52g2000cwj.googlegroups.com> Tom, W8JI wrote: "What you are missing is the flux inside the coil links all the turns at light speed. When it does that, current appears at nearly the same instant of time (light speed over the spatial distance of the inductor) in all areas that are linked by flux." Are any famous authors protagonists of that theory? One author, Bill Orr, W6SAI writes in the 22nd edition of "Radio Handbook" on page 5.11: "Spaced closely around the beam (in a TWT) is a circuit, in this case a helix of tightly wound wire, capable of propagating a slow wave. The r-f energy travels along the wire at the velocity of light but, because of the helical path, the energy progresses along the length of the tube at a considerably lower velocity that is determined by the pitch of the helix. Maybe Varian has a paper on this (just my speculation). Best regards, Richard Harrison, KB5WZI Article: 222517 of rec.radio.amateur.antenna From: ml Subject: Re: vert vs dipole gut comparison References: Message-ID: Date: Mon, 20 Mar 2006 10:18:39 GMT thanks very much to all those that replyed, but don't forget, we all agree that somtimes the dipole will work better sometimes the vert but the realy trick i wonder about is how many times will the vert be useful my guess is prob 50/50 but wasn't sure how 'random' it might all be In article , ml wrote: > hi > > > i am pondering this again after thinking the odds of being about to put > a beam up are slim > > currently i have a nice dipole CF horiz via a topside sgc , i am happy > w/it > > > i think i might be able to get a verticle (all bander) up there but then > i wonder > > overall if it would really pay from just a performance point of view > > the reviews i see i personally average as some signals would prob come > in bettter on one and some signals the other 'depending' > > but i guess i can't quantify if at the end of the day i'd say wow > really glad i had that vert or if perhaps having a 2nd antenna would > really net me only a marginal end of year bunch of extra qso's > > > perhaps a unrelated question #2 > > given the building master tv antenna is close by, would one guess that a > verticle or a small triband beam would give off more tvi?? > > > assume both would be slightly higher than the tv ant but close proximity > > thanks Article: 222518 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: antenna theory for idiots? Date: Mon, 20 Mar 2006 04:32:16 -0600 Message-ID: <2813-441E84B0-2247@storefull-3257.bay.webtv.net> References: Bob Miller was quoting the originaql questioner. Bob recommended "Better Shortwave Reception" by William Orr. Good advice, and the "Radio Handbook" recently published by Howard Sams and edited by William Orr is a good source of elementary theory too. Best regards, Richard Harrison, KB5WZI Article: 222519 of rec.radio.amateur.antenna Subject: Ink From: mshawjr@frontiernet.net Message-ID: <%WwTf.3014$tT.1641@news01.roc.ny> Date: Mon, 20 Mar 2006 12:08:27 GMT Sorry guys. The spam stuff was not my intent. I do oppoligies and won't happen again. I have never been on newsgroups before and not sure how to work them. I hope you guys can forgive a bad choice. Murphey Article: 222520 of rec.radio.amateur.antenna From: "Lisa Simpson" References: <2813-441E84B0-2247@storefull-3257.bay.webtv.net> Subject: Re: antenna theory for idiots? Message-ID: Date: Mon, 20 Mar 2006 12:39:51 GMT Thanx all! "Richard Harrison" wrote in message news:2813-441E84B0-2247@storefull-3257.bay.webtv.net... > Bob Miller was quoting the originaql questioner. > > Bob recommended "Better Shortwave Reception" by William Orr. Orderd from alibris.com for ~$6.00! Also orderd the ARRL handbook for ~$30 used! > > Good advice, and the "Radio Handbook" recently published by Howard Sams > and edited by William Orr is a good source of elementary theory too. > > Best regards, Richard Harrison, KB5WZI > Article: 222521 of rec.radio.amateur.antenna From: "Dave Turner" References: <%WwTf.3014$tT.1641@news01.roc.ny> Subject: Re: Ink Date: Mon, 20 Mar 2006 21:02:17 +0800 Message-ID: <441ea7aa@quokka.wn.com.au> wrote in message news:JTwTf.2739$tT.1678@news01.roc.ny... > Sorry guys. The spam stuff was not my intent. Yes it was, your header is still the same, and you've now re-spammed every newsgroup again with your 'apology'. It doesn't get any dumber. > I have never been on newsgroups before and not sure how to > work them. Yet you know how to spam them. Did you also learn to run before you could walk? > I hope you guys can forgive a bad choice. "You go to hell! You go to hell and you die!" - Mr Garrison Article: 222522 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121ojih732ucf6f@corp.supernews.com> <%Y3Tf.584343$qk4.104946@bgtnsc05-news.ops.worldnet.att.net> <121pmm3758jm4f4@corp.supernews.com> <8kqp12h5hs3bmrn2vn34i96m5fr0osv90s@4ax.com> <121q4fbgb89gb1a@corp.supernews.com> <121qh4dm7om8j13@corp.supernews.com> <1142813624.391779.279150@t31g2000cwb.googlegroups.com> <121s3k66tfvcq9d@corp.supernews.com> Message-ID: Date: Mon, 20 Mar 2006 15:24:10 GMT Roy Lewallen wrote: > When the ground was removed and replaced by a wire, the > transmission line properties of the coil changed dramatically, while the > C across the coil didn't change significantly. Moral: The self-resonant frequency of a loading-coil needs to be measured in the mobile antenna system, no on the bench. > Yes again, with one slight modification. You'll note from the EZNEC > models that the current actually increases some as you go up from the > bottom of the inductor. This is the effect noted by King which is due to > imperfect coupling between turns. It results in currents at both ends > being less than at the center. It results in a deviation away from the perfect cosine envelope exhibited by a 1/2WL thin-wire dipole. In any case, the delay through a 75m bugcatcher coil is tens of degrees, not 3 nS. > If the > reasons for this aren't obvious, many texts cover it quite well. No > special "traveling wave" analysis is required. The self-resonant frequency of that modeled coil is around 9 MHz. Since the coil is 90 degrees at 9 MHz, it would be ~59 degrees at 5.9 MHz. Dr. Corum suggests a 15 degree limit at which the lumped-circuit model needs to be abandoned in favor of the distributed-network model or Maxwell's equations. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222523 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121ojih732ucf6f@corp.supernews.com> <%Y3Tf.584343$qk4.104946@bgtnsc05-news.ops.worldnet.att.net> <121pmm3758jm4f4@corp.supernews.com> <8kqp12h5hs3bmrn2vn34i96m5fr0osv90s@4ax.com> <121q4fbgb89gb1a@corp.supernews.com> <121qh4dm7om8j13@corp.supernews.com> <1142813624.391779.279150@t31g2000cwb.googlegroups.com> <1142822019.697783.255030@z34g2000cwc.googlegroups.com> Message-ID: <5WzTf.40408$_S7.27437@newssvr14.news.prodigy.com> Date: Mon, 20 Mar 2006 15:32:17 GMT w8ji@akorn.net wrote: > You keep trying to drag something from a self-resonant helice into a > loading coil discussion. My 75m bugcatcher coil is self-resonant around 6.7 MHz so it meets the minimum requirement for a Tesla coil at 6.7 MHz. 4 MHz is 60% of the Tesla coil self-resonant frequency. The coil is known to possess a 90 degree delay at 6.7 MHz. That would make the delay ~60 degrees at 4 MHz. Dr. Corum suggests a 15 degree limit for the lumped-circuit model. > The two are nearly at opposite extremes in behavior, but even at that > the self-resonant helice can be analyzed with standar L/C analysis. Unfortunately, that's not true. One cannot assume the presuppositions of one's model without proof. The "standar L/C analysis " assumes the delay through a coil is zero, i.e. faster than light. The delay through a self-resonant coil is known to be 90 degrees. That "standar L/C" model is invalid at the self-resonant frequency where the coil is acting like a 1/4WL open-circuit transmission line stub. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222524 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121ojih732ucf6f@corp.supernews.com> <%Y3Tf.584343$qk4.104946@bgtnsc05-news.ops.worldnet.att.net> <121pmm3758jm4f4@corp.supernews.com> <8kqp12h5hs3bmrn2vn34i96m5fr0osv90s@4ax.com> <121q4fbgb89gb1a@corp.supernews.com> <121qh4dm7om8j13@corp.supernews.com> <1142813624.391779.279150@t31g2000cwb.googlegroups.com> <1142814316.040782.285000@i39g2000cwa.googlegroups.com> <1142822862.985006.247970@t31g2000cwb.googlegroups.com> Message-ID: <9_zTf.40409$_S7.5341@newssvr14.news.prodigy.com> Date: Mon, 20 Mar 2006 15:36:37 GMT w8ji@akorn.net wrote: > Yuri Blanarovich wrote: >>Cecil explained the various situation >>depending where the coil is placed within the radiator and at overall >>antenna curve. > > I doubt that. If he explained it in those terms he was missing some > important points. > I never claimed uniformly in ALL coils. I set boundaries as to the > conditions. I can replace that Hustler coil with another coil and ruin > your theory about standing waves and missing antenna degrees. Take your 1/4WL electrical antenna and put another 1/4WL bottom section beneath it. The current "flowing" into the bottom of the coil will be higher than the current "flowing" out of the top of the coil. Please explain that. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222525 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <121ojih732ucf6f@corp.supernews.com> <%Y3Tf.584343$qk4.104946@bgtnsc05-news.ops.worldnet.att.net> <121pmm3758jm4f4@corp.supernews.com> <8kqp12h5hs3bmrn2vn34i96m5fr0osv90s@4ax.com> <121q4fbgb89gb1a@corp.supernews.com> <121qh4dm7om8j13@corp.supernews.com> <1142813624.391779.279150@t31g2000cwb.googlegroups.com> <1142814316.040782.285000@i39g2000cwa.googlegroups.com> <1142822862.985006.247970@t31g2000cwb.googlegroups.com> <2upTf.185$wg6.164@fe10.lga> <1142850891.475736.293910@v46g2000cwv.googlegroups.com> Subject: Re: Current through coils Message-ID: Date: Mon, 20 Mar 2006 10:56:53 -0500 wrote in message news:1142850891.475736.293910@v46g2000cwv.googlegroups.com... > > Yuri Blanarovich wrote: >> >> Yea Tom, it all started with ALL coils, it is MY theory and you can ruin >> MY >> theory. > > What is your theory Yuri? > You didn't explain it. > 73 Tom > Nice twist again! (That was sarcasm and take on your comment about ALL coils) I didn't produce any MY theory. I simply realized that there is something weird (effect) when I burned heatshrink tubing on the bottom of my Hustler 80m coil, W9UCW measured and did experimenting with that and brought to our attention that there is significant difference in the current distribution across the loading coil. W5DXP put some explanations on as far as mechanism of the effect. I give credit where its due, I didn't produce any theory, I simply tried to bring attention to the effect, tried to find explanation and set the record straight for the benefit of hams, who were misled for decades (including myself), provide (with others) correction pointers so we can correctly model antennas and get better, more accurate results. If W7EL can capture the effect and provide tool to model the loading coil (lumped inductance) as what the hairpin of the same inductance does, we have a major improvement in modeling and designing loaded antennas and arrays. Sooo, we have the effect, we have some measurements to quantify it and we have explanations going back to Dr. Nikola Tesla and we are trying to set the record straight and correct the years of false information in the ham literature, going back to J. Belrose first article in ancient QST. What you have? Misinformation on your web site and refusing to admit that you could be wrong (again). Not answering technical questions, nitpicking on things to confuse and cloud the issue "proving" that you are right. Funny how you object to "personal" attacks, when it is the first thing you do when someone posts something that doesn't jive with your understanding of the subject. Been there, you have done it to me few times. Tom, it's not personal attack on YOU, it is correction ("attack") on what you (wrong) say and parade on your web site. The bottom line is, that you claim that loading antenna coil behaves according to "DC circuit laws" and has the same (or almost) current at both ends. When in reality there is quite a difference (talking about case of say quarter wave loaded radiator). The significance is, that the efficiency of the antenna is proportional to the area under the current distribution curve. If that distribution is portrayed wrongly (not showing, calculating drop of current across the coil) then we get false results, which will be magnified in multielement loaded array. So you can keep up the mumbo-jumbo and cloud the issue all you want, reality is there and won't go away. One more experiment that "scientwists" can do: Stick some neon bulbs at the bottom and top of the coil with equal "tail", or just move the neon bulb along the coil whil holding in your hand. I bet you would see that there is noticeable difference in brightness from top to bottom, top being brighter, meaning higher voltage. We know (not mine theory) that if voltage is higher then the current has to be lower, meaning that current at the bottom of the coil is higher than on the top. Meaning that it is not EQUAL as W8JI is insisting on. Nice science project for a 7th grader kid of a ham. (To avoid mumbo-jumbo detours - we are talking say 80m mobile Hustler or similar quarter wave antenna at resonant frequency). No need for phasors, distributed this or that, inside or outside of the coil wire and other "clouds". Can you answer questions that are posted, instead of sidestepping them and nitpicking on unrelated stuff? That's just MY theory, I may be wrong, and I would admit it, if I am shown the right. So can you ANSWER Cecil's question? Where did you get the engineering degree and usage of "JI Engineering"? Yuri, www.K3BU.us Article: 222526 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141772023.638201.196770@j52g2000cwj.googlegroups.com> <2813-441E7292-2246@storefull-3257.bay.webtv.net> Message-ID: Date: Mon, 20 Mar 2006 15:56:26 GMT Richard Harrison wrote: > Are any famous authors protagonists of that theory? > In "Fields and Waves in Modern Radio", Ramo and Whinnery, 2nd edition, there is a section titled: "9-16 The Idealized Helix and Other Slow-Wave Structures". Quoting: "A rough picture would convince one that the wave should follow the *wire* with about the velocity of light, ..." From the IEEE Dictionary: "slow-wave circuit - A circuit whose phase velocity is much slower than the velocity of light. For example, for suitably chosen helixes the wave can be considered to travel on the *wire* at the velocity of light but the phase velocity is less than the velocity of light by the factor that the pitch is less than the circumference." a 75m bugcatcher loading coil is a slow wave structure with a velocity factor around 0.017 (calculated and measured). -- 73, Cecil http://www.qsl.net/w5dxp Article: 222527 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: SWR Tells Me?? References: Message-ID: Date: Mon, 20 Mar 2006 16:00:50 GMT jimbo wrote: > OK, I have a new 2 meter j-pole antenna installed in my 3rd floor attic. > I have 50 feet of LMR240 coax running to the basement. I measure SWR at > the following frequencies on simplex. > > 144.2 2.5 > 145.2 2.4 > 146.2 2.3 > 147.2 1.9 > 147.9 1.7 > > Can I conclude that the antenna is electrically short for the 2 meter band? That's what I would conclude from the data given. Wind some wire around the tip top and extend the antenna by a few inches. Then repeat your SWR measurements. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222528 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: Subject: Re: vert vs dipole gut comparison Message-ID: Date: Mon, 20 Mar 2006 11:08:54 -0500 "ml" wrote > but don't forget, we all agree that somtimes the dipole will work better > sometimes the vert but the realy trick i wonder about is how many times > will the vert be useful > > my guess is prob 50/50 but wasn't sure how 'random' it might all be > To understand the benefits of vertical vs. dipole, one has to look at the radiation diagram of each antenna at particular height. Vertical has the lobes, where horizontal dipole has the nulls and vice versa. The other aspect is the polarization which plays bigger role in close range signals, long range DX signals have varying polarization after they go through the path. Then there are varying angles of arriving signal depending on propagation media. Another spect is that Vertical has omnidirectional pattern, while dipole has nulls in the pattern (off the ends). Depends how the antenna pattern and properties fit the current propagation mode/situation, that antenna would be better. So one has to look at the antenna pattern and have idea what propagation angles and polarization we are looking for. Verticals need good ground/soil/radials/salt water for better low angle performance. The answer to which is better: vertical or dipole is - YES, jus' depends wasaaaap (or down)! Yuri, www.K3BU.us Article: 222529 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: SWR Tells Me?? References: Message-ID: <%WATf.40428$_S7.20585@newssvr14.news.prodigy.com> Date: Mon, 20 Mar 2006 16:41:31 GMT kd5sak wrote: > "Cecil Moore" wrote in message >>Wind some >>wire around the tip top and extend the antenna by a few >>inches. Then repeat your SWR measurements. > > One might also try adjusting the feed point location and see what effect > that has. That would be good to do after adjusting the length. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222530 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Current through coils Date: Mon, 20 Mar 2006 17:17:34 +0000 (UTC) Message-ID: References: <121ojih732ucf6f@corp.supernews.com> <%Y3Tf.584343$qk4.104946@bgtnsc05-news.ops.worldnet.att.net> <121pmm3758jm4f4@corp.supernews.com> <8kqp12h5hs3bmrn2vn34i96m5fr0osv90s@4ax.com> <121q4fbgb89gb1a@corp.supernews.com> <121qh4dm7om8j13@corp.supernews.com> <1142813624.391779.279150@t31g2000cwb.googlegroups.com> <1142814316.040782.285000@i39g2000cwa.googlegroups.com> <1142822862.985006.247970@t31g2000cwb.googlegroups.com> <2upTf.185$wg6.164@fe10.lga> <1142850891.475736.293910@v46g2000cwv.googlegroups.com> Yuri, why not try program LOADCOIL. Its just what you've been waiting for. Download from website below. ---- ........................................................... Regards from Reg, G4FGQ For Free Radio Design Software go to http://www.btinternet.com/~g4fgq.regp ........................................................... Article: 222531 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121ojih732ucf6f@corp.supernews.com> <%Y3Tf.584343$qk4.104946@bgtnsc05-news.ops.worldnet.att.net> <121pmm3758jm4f4@corp.supernews.com> <8kqp12h5hs3bmrn2vn34i96m5fr0osv90s@4ax.com> <121q4fbgb89gb1a@corp.supernews.com> <121qh4dm7om8j13@corp.supernews.com> <1142813624.391779.279150@t31g2000cwb.googlegroups.com> <1142814316.040782.285000@i39g2000cwa.googlegroups.com> <1142822862.985006.247970@t31g2000cwb.googlegroups.com> Message-ID: Date: Mon, 20 Mar 2006 17:26:43 GMT w8ji@akorn.net wrote: > 1.) I can build an antenna that has greatly uneven currents at the ends > of the loading coil, but the antenna rea above the inductor is wasted > and the system will be less efficient than a properly designed system. Anyone with EZNEC can answer the question for himself. For the following EZ files, the currents at the bottom and top of the coil are viewed by clicking on the "Load Dat" button. Load 1 is at the bottom of the coil and Load 2 is at the top of the coil. The loads are both zero so they have no effect on the antenna system and are used only to report the current at that point. I previously modeled a bottom-loaded 5.89 MHz mobile antenna. That EZNEC file is available at: http://www.qsl.net/w5dxp/test316.EZ Taking that antenna and *changing nothing* except adding 1/4WL of wire to the top of the whip, yields the EZNEC file at: http://www.qsl.net/w5dxp/test316c.EZ The antenna has been changed from a base-loaded 1/4WL antenna to a base-loaded 1/2WL antenna using the same coil in the same relative position to the source and ground. The changes in the currents through the coil are obvious. The frequency was not changed so the coil occupies the same percentage wavelength of the antenna in both examples. In the first example, we have 1.01 amps at the bottom of the coil and 0.6984 amps at the top of the coil. That's fairly typical for mobile antennas at the 5.89 MHz frequency and agrees with the measurements presented so far. Now, changing nothing except the whip length by adding 40 feet (1/4WL) of whip, in the second example we have 1.239 amps at the bottom of the coil and 2.068 amps at the top of the coil. How does the lumped-circuit model explain that one? More current "flowing" into the coil than is "flowing" out of the coil just by adding 40' of wire to the top of the antenna? The coil occupies the same electrical length in both examples because they are at the same frequency. The current through the coil depends upon where it is physically installed relative to the standing waves existing at the point of installation. Using what EZNEC tells us about the self-resonant frequency near 9 MHz, we can calculate the delay through the coil as ~59 degrees. Thus the coil occupies ~0.16 wavelength. (The wire used to wind the coil is ~0.24 wavelength if stretched out straight.) Nobody said it was a 1:1 replacement but someone said it was *NOT* a replacement at all. I would encourage the experimenters to add 1/4WL of whip to their previously measured mobile antenna systems and make additional measurement. That is, of course, after matching the source to the new impedance. Please report the results here. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222532 of rec.radio.amateur.antenna From: Michael Coslo Subject: Re: First Attempt Date: Mon, 20 Mar 2006 12:31:08 -0500 Message-ID: References: Old Ed wrote: > Reg, > > The type of antenna you describe is very useful and popular. > > However, your assertion is much too sweeping as a generalization. > In no particular order, here are some caveats: > 1. The qualifier "best" is largely meaningless, absent an agreed > set of weighted criteria for "goodness." (How important is: > size? weight? cost? visual profile? bandwidth? instant QSY? > gain? pattern? low-band performance vs. high-band performance? > power-handling capacity? need for tuner? etc., etc., etc.) I'm always hesitant to use words like "best" for all the reasons you state, but I think that Reg qualified things pretty well. Within the qualifications of all band dipoles, the ladder-line fed general dipole is pretty darn hard to beat. I recommend them to any new hams that ask me for advice on antennas. My rationale is that most new hams these days buy rigs that are all-band, transistorized units.These units are also sensitive to mismatches between antenna and rig. Most new hams are not antenna gurus either. So here is an antenna that will allow them to get on the air without a lot of fussing. The only real measurement caveats are some lengths that you don't want to use. So we end up with an antenna that allows the newbie to get on the air, allows them to learn some stuff by twiddling knobs and such, then when they have a bit more experience, they can tackle that more "advanced antenna" with it's more exacting design, trimming , and measurements. > 2. A good case can be made that choosing the "right" length is > "better" than a random length, within this type. > 3. An excellent case can be made that center-fed is NOT always > the "best" option, within this type. > 4. I'll let the fans of this antenna type chime in with why they > prefer balanced tuners and/or tuned feeders to the use of an > unbalanced tuner... if they want to. (I use more tailored antennas, > and don't need a tuner of any kind, most of the time.) As I do now. I've really been smitten with my OCF dipole, fed with Coax, because in no small part, the feedpoint drops straight down to my shack. That coupled with an automatic tuner in my radio , allowing me to "plug and play. But I still strongly urge newcomers to put up one of those ladder line dipoles for the experience. They work okay, too! 8^) > > "Reg Edwards" wrote in message > news:dvhp20$ap9$1@nwrdmz01.dmz.ncs.ea.ibs-infra.bt.com... >> The best, all round, all band, antenna is a high centre-fed dipole of >> no particular length, fed with an open-wire feedline of no particular >> length or impedance, all the way to the shack, used with a choke-balun >> and an unbalanced tuner. >> >> It is good down to the frequency at which the dipole is about >> 1/3-wavelength long. >> >> Simplicity = efficiency. >> >> Once tried you will never return to anything else. >> ---- >> Reg. >> >> > > Article: 222533 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Current through coils Date: Mon, 20 Mar 2006 17:34:11 +0000 (UTC) Message-ID: References: <121ojih732ucf6f@corp.supernews.com> <%Y3Tf.584343$qk4.104946@bgtnsc05-news.ops.worldnet.att.net> <121pmm3758jm4f4@corp.supernews.com> <8kqp12h5hs3bmrn2vn34i96m5fr0osv90s@4ax.com> <121q4fbgb89gb1a@corp.supernews.com> <121qh4dm7om8j13@corp.supernews.com> <1142813624.391779.279150@t31g2000cwb.googlegroups.com> <121s3k66tfvcq9d@corp.supernews.com> Cec, who the heck is Dr Corum? Is he yet another Bible writer? Nobody's ever heard of him. What makes you think he is right? Is it just because you think he agrees with YOU? And you may have taken him out of context and misquoted him anyway. ---- Reg. Article: 222534 of rec.radio.amateur.antenna From: Michael Coslo Subject: Re: vert vs dipole gut comparison Date: Mon, 20 Mar 2006 12:40:38 -0500 Message-ID: References: <80bs125aalppg522mun6hr442egt3bk97i@4ax.com> Owen Duffy wrote: > On Sun, 19 Mar 2006 22:15:00 -0500, Mike Coslo > wrote: > > >> Some times the vertical works better, and sometimes the horizontal >> works better. I'm having a heck of a time correlating exactly *why and > > Mike, we need a clear definition of the meaning of "works" in your > data gathering and analysis. Yeah! I'm trying to come up with a good test protocol that will allow me to define "work". So far, I can note that some signals drop into the noise and become unreadable, while are readable on the other at the same time. That seems a bit simplistic though. My main problem is the variable signal levels., and the also variable noise levels. Turns out that the antenna that was noisier on one band is quieter on another, and vice versa. A fellow could come to the conclusion that "this ain't exactly easy". HA! - 73 de Mike KB3EIA - Article: 222535 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Current through coils Date: Mon, 20 Mar 2006 17:42:12 +0000 (UTC) Message-ID: References: <1141772023.638201.196770@j52g2000cwj.googlegroups.com> <2813-441E7292-2246@storefull-3257.bay.webtv.net> Everybody quotes from Bibles. Which reduces the authors to the same standard of conversation as transpires on this newsgroup. Has nobody any confidence in what he is saying and feels in need of support from the angeles. ------------------------------------------------------------------- Article: 222536 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121ojih732ucf6f@corp.supernews.com> <%Y3Tf.584343$qk4.104946@bgtnsc05-news.ops.worldnet.att.net> <121pmm3758jm4f4@corp.supernews.com> <8kqp12h5hs3bmrn2vn34i96m5fr0osv90s@4ax.com> <121q4fbgb89gb1a@corp.supernews.com> <121qh4dm7om8j13@corp.supernews.com> <1142813624.391779.279150@t31g2000cwb.googlegroups.com> <121s3k66tfvcq9d@corp.supernews.com> Message-ID: Date: Mon, 20 Mar 2006 17:49:39 GMT Reg Edwards wrote: > Cec, who the heck is Dr Corum? Nobody's ever heard of him. Reg, in Mexico, it's known as a "Tequila Sunrise". In your case, it must be a "Chardoney Sunrise". :-) If you've never heard of him, it's your own fault. http://www.ttr.com/corum/index.htm http://www.ttr.com/TELSIKS2001-MASTER-1.pdf - URLs posted here a number of times. Do a web search to understand his far-reaching influence in matters of a technical nature. > What makes you think he is right? He makes sense and his equations agree with my rough measurements within 14%. I suspect my measurements are off by at lease 10%. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222537 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141772023.638201.196770@j52g2000cwj.googlegroups.com> <2813-441E7292-2246@storefull-3257.bay.webtv.net> Message-ID: Date: Mon, 20 Mar 2006 17:52:29 GMT Reg Edwards wrote: > Has nobody any confidence in what he is saying and feels in need of > support from the angeles. "angeles"? Resorting to Spanish is no help. The present question is, "can EZNEC be trusted"? We already know your opinion. :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 222538 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: SWR Tells Me?? Date: Mon, 20 Mar 2006 18:05:33 +0000 (UTC) Message-ID: References: Jimbo, The most likely source of variation is inaccuracy of your SWR meter. It doesn't measure SWR on the feedline anyway. The questions you should ask is does it work? And is the transmitter roughly loaded with the right load impedance? ---- Reg Article: 222539 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Current through coils Date: Mon, 20 Mar 2006 18:24:07 +0000 (UTC) Message-ID: References: <1141772023.638201.196770@j52g2000cwj.googlegroups.com> <2813-441E7292-2246@storefull-3257.bay.webtv.net> "Cecil Moore" wrote > Reg Edwards wrote: > > Has nobody any confidence in what he is saying and feels in need of > > support from the angeles. > > "angeles"? Resorting to Spanish is no help. The present > question is, "can EZNEC be trusted"? We already know > your opinion. :-) ======================================== Dear Cec, - - - and what is my opinon which everybody is supposed to know? C'mon then. Be truthful. Out with it! ---- Reg. Article: 222540 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141772023.638201.196770@j52g2000cwj.googlegroups.com> <2813-441E7292-2246@storefull-3257.bay.webtv.net> Message-ID: Date: Mon, 20 Mar 2006 19:14:28 GMT Reg Edwards wrote: > - - - and what is my opinon which everybody is supposed to know? > C'mon then. Be truthful. Out with it! Your opinion of EZNEC is recorded for posterity on Google. Who am I to embellish it? -- 73, Cecil http://www.qsl.net/w5dxp Article: 222541 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121ojih732ucf6f@corp.supernews.com> <%Y3Tf.584343$qk4.104946@bgtnsc05-news.ops.worldnet.att.net> <121pmm3758jm4f4@corp.supernews.com> <8kqp12h5hs3bmrn2vn34i96m5fr0osv90s@4ax.com> <121q4fbgb89gb1a@corp.supernews.com> <121qh4dm7om8j13@corp.supernews.com> <1142813624.391779.279150@t31g2000cwb.googlegroups.com> <1142814316.040782.285000@i39g2000cwa.googlegroups.com> <1142822862.985006.247970@t31g2000cwb.googlegroups.com> Message-ID: <9eDTf.56363$H71.25315@newssvr13.news.prodigy.com> Date: Mon, 20 Mar 2006 19:18:29 GMT Cecil Moore wrote: > w8ji@akorn.net wrote: >> 1.) I can build an antenna that has greatly uneven currents at the ends >> of the loading coil, but the antenna rea above the inductor is wasted >> and the system will be less efficient than a properly designed system. > > Anyone with EZNEC can answer the question for himself. In accordance with my policy of correcting my mistakes using the scientific method and updating my presentations to have the most impact, I have revised the bottom of the web page at http://www.qsl.net/w5dxp/current.htm Can there be any question about the lumped-circuit model failing in a standing wave environment after viewing that information? -- 73, Cecil http://www.qsl.net/w5dxp Article: 222542 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: vert vs dipole gut comparison Date: Mon, 20 Mar 2006 11:32:05 -0800 Message-ID: <121u0posj1cgt85@corp.supernews.com> References: <80bs125aalppg522mun6hr442egt3bk97i@4ax.com> Michael Coslo wrote: > > Yeah! I'm trying to come up with a good test protocol that will > allow me to define "work". > > So far, I can note that some signals drop into the noise and become > unreadable, while are readable on the other at the same time. That seems > a bit simplistic though. > > My main problem is the variable signal levels., and the also > variable noise levels. Turns out that the antenna that was noisier on > one band is quieter on another, and vice versa. > > A fellow could come to the conclusion that "this ain't exactly > easy". HA! It isn't. The best antenna for transmitting is the one which produces the loudest signal at the other station. The best antenna for receiving is the one which produces the best signal/noise ratio at your station. The two are often different, because they're determined by different antenna characteristics. So for starters, you can have two "best" antennas for each station you want to contact, and that "best" will vary with the skip elevation angle, local noise level, and directions and angles the noise is coming from. Have fun! Roy Lewallen, W7EL Article: 222543 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141772023.638201.196770@j52g2000cwj.googlegroups.com> <2813-441E7292-2246@storefull-3257.bay.webtv.net> Message-ID: Date: Mon, 20 Mar 2006 19:35:40 GMT Richard Clark wrote: > Cecil Moore wrote: >>The present question is, "can EZNEC be trusted"? > > This repugnant "question" borders on, and crosses into ignorance for > the sake of arguing. It was a rhetorical question, Richard. If the creator of EZNEC disagrees with his own creation, what does that imply? -- 73, Cecil http://www.qsl.net/w5dxp Article: 222544 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Current through coils Date: Mon, 20 Mar 2006 12:00:56 -0800 Message-ID: <121u2fs34bn1he1@corp.supernews.com> References: <1141772023.638201.196770@j52g2000cwj.googlegroups.com> <2813-441E7292-2246@storefull-3257.bay.webtv.net> Richard Clark wrote: > On Mon, 20 Mar 2006 17:52:29 GMT, Cecil Moore > wrote: >> The present question is, "can EZNEC be trusted"? > This repugnant "question" borders on, and crosses into ignorance for > the sake of arguing. Hm. Cecil was quick to hold up EZNEC results as evidence when they seemed to support his theory. He must have come across a situation where they didn't. EZNEC can indeed be trusted. There are of course some cases where the underlying NEC calculating engines have limitations or run into numerical trouble, but those are quite well known and documented. So far, the models and EZNEC results I've seen here -- from Cecil's models and from the modified model I made -- are easily within EZNEC's capabilities and agree with known theory. This shouldn't be a surprise to anyone. If they disagree with some alternate theory, the alternate theory is faulty. Promoters of antennas with magical properties often say that their antenna can't be modeled because the modeling programs don't "take into account" whatever magical effect they've dreamed up to justify their impossible claims. That's their way of trying to explain why modeling programs show their claims to be false. I detect the same phenomenon happening here. EZNEC and NEC are being used daily by hundreds or thousands of companies, government agencies, military groups, and universities to aid in designing antennas that work, and NEC has been in use for nearly 30 years now. We make use of them daily. EZNEC is indeed trusted, by some of the biggest and most sophisticated aerospace companies and government agencies. If anyone ever sees a significant difference between EZNEC and NEC results, please let me know so I can track down the reason. Roy Lewallen, W7EL Article: 222545 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Current through coils Date: Mon, 20 Mar 2006 20:43:37 +0000 (UTC) Message-ID: References: <1141772023.638201.196770@j52g2000cwj.googlegroups.com> <2813-441E7292-2246@storefull-3257.bay.webtv.net> "Cecil Moore" wrote > Your opinion of EZNEC is recorded for posterity on Google. > Who am I to embellish it? ========================= Cecil, as usual you are being hopelessly evasive. ---- Reg. Article: 222546 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141772023.638201.196770@j52g2000cwj.googlegroups.com> <2813-441E7292-2246@storefull-3257.bay.webtv.net> <121u2fs34bn1he1@corp.supernews.com> Message-ID: Date: Mon, 20 Mar 2006 21:04:32 GMT Roy Lewallen wrote: > Richard Clark wrote: > >> Cecil Moore wrote: >>> The present question is, "can EZNEC be trusted"? >> >> This repugnant "question" borders on, and crosses into ignorance for >> the sake of arguing. > > Hm. Cecil was quick to hold up EZNEC results as evidence when they > seemed to support his theory. He must have come across a situation where > they didn't. On the contrary, Roy, it was a ***rhetorical*** question to which Richard kindly responded. It is you who are disagreeing with the EZNEC results, which are your own creation. I fully agree with the EZNEC results posted below. So are you or EZNEC correct? Both you and EZNEC be correct. Please see: http://www.qsl.net/w5dxp/current.htm and scroll down to the bottom. > EZNEC can indeed be trusted. Glad to hear you say that, Roy. Does that imply that you cannot be trusted? (Another rhetorical question) Reckon why the EZENC results disagree with your personal postings on this newsgroup? -- 73, Cecil http://www.qsl.net/w5dxp Article: 222547 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141772023.638201.196770@j52g2000cwj.googlegroups.com> <2813-441E7292-2246@storefull-3257.bay.webtv.net> <2u2u12lu12sqdrb8mkeev8j9on8otchotk@4ax.com> Message-ID: <8QETf.48890$F_3.7390@newssvr29.news.prodigy.net> Date: Mon, 20 Mar 2006 21:07:16 GMT Richard Clark wrote: > This prelude to more ignorance reveals moral equivocation. Actually, your naivite' in following me down the primrose path is enlightening. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222548 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141772023.638201.196770@j52g2000cwj.googlegroups.com> <2813-441E7292-2246@storefull-3257.bay.webtv.net> Message-ID: Date: Mon, 20 Mar 2006 21:10:42 GMT Reg Edwards wrote: > "Cecil Moore" wrote >>Your opinion of EZNEC is recorded for posterity on Google. >>Who am I to embellish it? > > Cecil, as usual you are being hopelessly evasive. I could waste my time Googling your opinion of EZNEC but why should I waste my valuable time doing that? -- 73, Cecil http://www.qsl.net/w5dxp Article: 222549 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: SWR Tells Me?? Message-ID: References: Date: Mon, 20 Mar 2006 21:27:33 GMT On Mon, 20 Mar 2006 15:37:26 -0500, Dave wrote: >In your set up the VSWR tells you very little!! > >That 50 feet of LMR240 is modifying the actual VSWR as seen at your >meter. It is not telling you the VSWR at the feed point. The matched line loss of 50' LMR240 at 146MHz is 1.5dB. Jimbo tells us the source end VSWR at 146.2 is 2.3. One can make a reasonable estimate that the VSWR at the antenna end of the line is 3.5 (not a very good match for an antenna that should use an adjustable matching system). Total line loss is around 2.3dB, or about 0.9dB worse than matched line loss. Now look at the tx output power, has it decreased because of the bad load. Add that reduction (in dB) to the 0.9% above to get the overall degradation of transmit perfomance. A question: Is the proximity of other structures or feedline isolation a cause of the high VSWR, and should you resolve that before tweaking the matching? Owen -- Article: 222550 of rec.radio.amateur.antenna From: Bob Miller Subject: Re: SWR Tells Me?? Message-ID: References: Date: Mon, 20 Mar 2006 21:31:02 GMT On Mon, 20 Mar 2006 15:37:26 -0500, Dave wrote: >In your set up the VSWR tells you very little!! > >That 50 feet of LMR240 is modifying the actual VSWR as seen at your >meter. It is not telling you the VSWR at the feed point. > >First, the antenna should have a balanced feed. With coax you need a 1/2 >wavelength [coax corrected for velocity factor] matching stub to keep >the line balanced. This will minimized coupling antenna current on the >outside of the coax cable. > >Second, you should measure the antenna feed point impedance at the >feedpoint, or 1/2 wavelength from the feed point [coax corrected for >velocity factor]. I'm confused, wouldn't it be more important to have the right impedance and swr at the end of the feedline, where the transceiver is expecting 50 ohms? bob k5qwg > >Third, adjust the feedpoint location to get 50 + j0 ohms on your >preferred frequency using an antenna analyzer [one or more members of >your radio club should have one]. > >I'm located in southern NH, USA and if you are reasonably close I can >assist in tuning your antenna. > >DD > >jimbo wrote: > >> OK, I have a new 2 meter j-pole antenna installed in my 3rd floor attic. >> I have 50 feet of LMR240 coax running to the basement. I measure SWR at >> the following frequencies on simplex. >> >> 144.2 2.5 >> 145.2 2.4 >> 146.2 2.3 >> 147.2 1.9 >> 147.9 1.7 >> >> Can I conclude that the antenna is electrically short for the 2 meter band? >> >> Thanks for any insight, jimbo Article: 222551 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: vert vs dipole gut comparison Message-ID: <3f7u12l4b75i5ne21vcq3at51f00m97qoo@4ax.com> References: <80bs125aalppg522mun6hr442egt3bk97i@4ax.com> <121u0posj1cgt85@corp.supernews.com> Date: Mon, 20 Mar 2006 21:35:48 GMT On Mon, 20 Mar 2006 11:32:05 -0800, Roy Lewallen wrote: >> A fellow could come to the conclusion that "this ain't exactly >> easy". HA! > >It isn't. > >The best antenna for transmitting is the one which produces the loudest >signal at the other station. The best antenna for receiving is the one >which produces the best signal/noise ratio at your station. The two are >often different, because they're determined by different antenna >characteristics. So for starters, you can have two "best" antennas for >each station you want to contact, and that "best" will vary with the >skip elevation angle, local noise level, and directions and angles the >noise is coming from. > Just was I was thinking when I prompted the "works" definition. I should not be surprised if many observations indicate the better antenna for tx is different from the better antenna for rx. I am not trying to question reciprocity, but there are several factors, ambient noise at the rx site probably being the most significant. Key thing is, works is not adequately defined by making one or a few DX QSOs!. Mike, perhaps you need to formalise your "works" criteria with your current experience, identifying what you need to record, before making too many more observations. I agree with Roy, for each antenna, rx main figure of merit S/N (crudely S units between ambient noise and signal), and on tx, the other stations observed S meter reading. (Whole log of issues there... but a rough start supported by the current RST reporting scheme.) Owen -- Article: 222552 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: SWR Tells Me?? Message-ID: References: Date: Mon, 20 Mar 2006 21:43:42 GMT On Mon, 20 Mar 2006 21:31:02 GMT, Bob Miller wrote: >>Second, you should measure the antenna feed point impedance at the >>feedpoint, or 1/2 wavelength from the feed point [coax corrected for >>velocity factor]. > Why the half wavelength? The VSWR in this situation varies smoothly from the value at the feed point to the value at the source end of the line as dictated by the (known) line loss. In this scenario, knowing matched line loss and the VSWR at a point, it is possible to estimate the VSWR anywhere else on the line (as I have done in another post). >I'm confused, wouldn't it be more important to have the right >impedance and swr at the end of the feedline, where the transceiver is >expecting 50 ohms? There are two objectives: 1. delivering the transmitter its rated load impedance (so that it safely delivers its rated power); 2. minimising line loss. 1. is achieved by a load approximately 50 ohms at the souce end of the line. 2. is achieved by a load approximately 50 ohms at the load end of the line (which will also satisfy 1.). Owen -- Article: 222553 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: SWR Tells Me?? References: Message-ID: <_XFTf.45503$2O6.22847@newssvr12.news.prodigy.com> Date: Mon, 20 Mar 2006 22:23:54 GMT jimbo wrote: > I am not sure what you mean by "wrap some wire around the tip top." I > could splice some wire on the long leg of the ladder line? The antenna appears to be too short. Lengthen the antenna, normally accomplished at the tip top. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222554 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141772023.638201.196770@j52g2000cwj.googlegroups.com> <2813-441E7292-2246@storefull-3257.bay.webtv.net> <121u2fs34bn1he1@corp.supernews.com> Message-ID: Date: Mon, 20 Mar 2006 23:10:15 GMT Richard Clark wrote: > Cecil Moore wrote: >>Does that imply that you cannot >>be trusted? (Another rhetorical question) > > Even rhetorical questions cannot cloak their repugnant character. Certainly, no repugnance or disrespect intended. Roy is presently in the unenviable position of agreeing with (EZNEC and me) or disagreeing with (EZNEC and me). Hint: rhetorical questions require no answer. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222555 of rec.radio.amateur.antenna From: Allison-nospam@nouce.bellatlantic.net Subject: Re: SWR Tells Me?? Message-ID: References: Date: Mon, 20 Mar 2006 23:11:33 GMT On Mon, 20 Mar 2006 17:51:28 -0500, Dave wrote: >Bob Miller wrote: > >SNIPPED >> >> I'm confused, wouldn't it be more important to have the right >> impedance and swr at the end of the feedline, where the transceiver is >> expecting 50 ohms? >> >> bob >> k5qwg >> > >SNIPPED > >If you have 50 ohms at the antenna, then you will have 50 ohms >regardless of the length of coax. > >A 3:1 VSWR, assuming other responses to this post are correct, means >that your antenna connection could be anything from 16 ohms to 150 ohms >and all sorts of combinations of resistance and reactance within that range. > >An antenna analyzer will let you determine antenna resonance, antenna >feedpoint impedance [hopefully 50 ohms], coax line loss, and allow >proper adjustment at the connection points for your coax. > >Once again, find someone in your area with an antenna analyzer. I repeat >my offer if you are within 60 +/- miles of Concord NH. It's possible to tune a Jpole with just a SWR meter. I've done ti many times though it's more tedious than with an antenna analyser. The simplest step is add some length to the long section, not alot and see how the change affects it. Add more or less as needed for a good minimum. If the minimum is still not on the mark (1:1 is ideal but anything under 1.3:1 flies well) then adjust the tap point (very small movements) and resweep again. With patience you (the person that asked) will get it right. What happens with Jpoles is they often are not built identical and small differences do show. Also like most halfwave and larger antennas being close to "stuff" tends to affect tuning. No harm or foul but learning to prune (aka tune) an atenna is a skill and worth developing. Allison KB1GMX Article: 222556 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: SWR Tells Me?? Message-ID: <6mdu12te5gkm3kraf4pkvkehkcq30fm4b0@4ax.com> References: Date: Mon, 20 Mar 2006 23:18:10 GMT On Mon, 20 Mar 2006 17:54:19 -0500, Dave wrote: >Owen Duffy wrote: > >> On Mon, 20 Mar 2006 21:31:02 GMT, Bob Miller >> wrote: >> >> >> >>>>Second, you should measure the antenna feed point impedance at the >>>>feedpoint, or 1/2 wavelength from the feed point [coax corrected for >>>>velocity factor]. >>> >> >> Why the half wavelength? >> >> > >A 1/2 wavelength transmission line repeats the load impedance at the >antenna with minimum loss, assuming you cannot get an analyzer at the >antenna itself. > >IMO, measuring directly at the antenna and solving the matching/load >problem there is the easiest and best method. You are free to disagree. Ok, but again you can measure the impedance anywhere and knowing line parameters, calculate Z at any other point. Owen -- Article: 222557 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <2813-441E7292-2246@storefull-3257.bay.webtv.net> <121u2fs34bn1he1@corp.supernews.com> <70eu129ccenpl354f90odhsacri3rc6kih@4ax.com> Message-ID: Date: Mon, 20 Mar 2006 23:41:17 GMT Richard Clark wrote: > (and quite commonly from you, anyone) is sleazy > rhetoric. No matter what I say, you consider it to be sleazy rhetoric, Richard. It's not my problem. I have been telling Roy this basic technical stuff for three years or more. It's also not my problem. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222558 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: vert vs dipole gut comparison References: <1142897819.468971.52560@i40g2000cwc.googlegroups.com> Message-ID: <86HTf.3411$tN3.1493@newssvr27.news.prodigy.net> Date: Mon, 20 Mar 2006 23:43:00 GMT fazamy@aol.com wrote: > Is the polarity of the sending station and receiving station relevant > to this discussion?? Yes on ground wave VHF/UHF. No on HF skip. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222559 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: vert vs dipole gut comparison References: <1142897819.468971.52560@i40g2000cwc.googlegroups.com> <86HTf.3411$tN3.1493@newssvr27.news.prodigy.net> Message-ID: <1iHTf.3414$tN3.2471@newssvr27.news.prodigy.net> Date: Mon, 20 Mar 2006 23:55:41 GMT Cecil Moore wrote: > fazamy@aol.com wrote: > >> Is the polarity of the sending station and receiving station relevant >> to this discussion?? > > Yes on ground wave VHF/UHF. No on HF skip. Oops, lest some nitpicker jump in, I should have said "surface wave", not "ground wave". And I probably should have included a "usually" while I was at it. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222560 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: SWR Tells Me?? Message-ID: <5jgu12hcv5i5bg0ijf8k1t75vuio21070c@4ax.com> References: Date: Tue, 21 Mar 2006 00:10:00 GMT On Mon, 20 Mar 2006 16:51:44 -0700, jimbo wrote: >Owen Duffy wrote: >> On Mon, 20 Mar 2006 15:37:26 -0500, Dave wrote: >> >> >>>In your set up the VSWR tells you very little!! >>> >>>That 50 feet of LMR240 is modifying the actual VSWR as seen at your >>>meter. It is not telling you the VSWR at the feed point. >> >> >> The matched line loss of 50' LMR240 at 146MHz is 1.5dB. >> >> Jimbo tells us the source end VSWR at 146.2 is 2.3. One can make a >> reasonable estimate that the VSWR at the antenna end of the line is >> 3.5 (not a very good match for an antenna that should use an >> adjustable matching system). Total line loss is around 2.3dB, or about >> 0.9dB worse than matched line loss. >> >> Now look at the tx output power, has it decreased because of the bad >> load. Add that reduction (in dB) to the 0.9% above to get the overall >> degradation of transmit perfomance. >> >> A question: Is the proximity of other structures or feedline isolation >> a cause of the high VSWR, and should you resolve that before tweaking >> the matching? >> >> Owen >> -- > One step at a time... >The numbers are confusing. 50 feet of LMR240 1.5 dB, (I understand >that.) Ok. > Total line loss 2.3 dB. (Where did you get that?) It can be calculated knowing the line loss and source end VSWR. The additional 0.8dB is increased line loss due to operation with VSWR>1. Try http://www.vk1od.net/tl/tllce.php for the calcs. > .9 dB worse >than matched line loss. (Where did you get that number?) Sorry, my rounding error, call it 0.8dB. It is by subtraction of the matched line loss from the total line loss. > >There is wooden structure near since the antenna is located in an >attic. But I don't think there are any large metal structures close to >the antenna. The coax is in PVC pipe. It may go close to a metal AC >duct on it's way to the basement.. Is the roof sarked (does it have a metal foil lining under the tiles or shingles), presumably it isnt a metal roof. > >Thanks, jimbo -- Article: 222561 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: SWR Tells Me?? Message-ID: References: <6mdu12te5gkm3kraf4pkvkehkcq30fm4b0@4ax.com> Date: Tue, 21 Mar 2006 00:15:04 GMT On Mon, 20 Mar 2006 19:00:16 -0500, Dave wrote: >Owen Duffy wrote: > >SNIPPED >> >> Ok, but again you can measure the impedance anywhere and knowing line >> parameters, calculate Z at any other point. >> >> Owen >> -- > >Owen, I don't disagree with you. But, IMO, it is beyond Bob Miller's >expertise/knowledge, at this point in his ham experience, to perform >those calculations. > >I didn't perform those calculations until my 3rd year in engineering school. > >KISS, and fix it at the source. Dave, there is no doubt that the closer you are to the antenna, the less error introduced by tolerance on line parameters. On the otherhand, the instrumentation / user can be disruptive or real inconvenient. As for the calcs, one can be lazy and use http://www.vk1od.net/tl/tllce.php (if one's cable type is supported). My antenna analyser can't do the calcs internally, I don't know if some can, but it would be a pretty handy feature. Owen -- Article: 222562 of rec.radio.amateur.antenna From: "Steve Nosko" Subject: Re: SWR Tells Me?? Date: Mon, 20 Mar 2006 18:32:02 -0600 Message-ID: References: But-out flag cleared// "jimbo" wrote in message news:yZOdnZUtoLx6uoLZnZ2dnUVZ_tydnZ2d@comcast.com... > Dave wrote: > > In your set up the VSWR tells you very little!! > > > > That 50 feet of LMR240 is modifying the actual VSWR as seen at your > > meter. It is not telling you the VSWR at the feed point.... > > > > Second, you should measure the antenna feed point impedance at the > > feedpoint, or 1/2 wavelength from the feed point [coax corrected for > > velocity factor]. > > ..... > > > > DD > > > > jimbo wrote: > > > >> OK, I have a new 2 meter j-pole antenna installed in my 3rd floor > >> attic. I have 50 feet of LMR240 coax running to the basement. I > >> measure SWR at the following frequencies on simplex. > >> > >> 144.2 2.5 > >> 145.2 2.4 > >> 146.2 2.3 > >> 147.2 1.9 > >> 147.9 1.7 > >> > >> Can I conclude that the antenna is electrically short for the 2 meter > >> band? > >> > >> Thanks for any insight, jimbo Seems to me there are several items being asked / answered here. Sort of going backwards through the parts of the thread I can see... 1 - I think it is a safe bet that if the VSWR at the transmitter (regardless of feed like loss BUT within normally expected values) is lowest at the high end of the band, then the antenna system is either too short or resonant too high in frequency - take your pick of wording. 2- As you measure VSWR further and further from the load (antenna) you will get a better and better value because of the loss in the transmission line. This is because as signal is lost to the loss (attenuation) of the line, there is less to reflect at the load and less makes it back to the measuring device - when compared to tehat sent from teh transmitter. Less power to measure in the backward direction = better VSWR. Side Note that the loss is twice the line loss in this case, because it travels it twice in a round trip. Another result of this is that a simple resistive (lossy) attenuator (or a hunk of t-line used as an attenuator) has a return loss that is equal to twice its attenuation rating. In other words, a 10dB pad has a 20 dB return loss and is a pretty good load, since only 1% of the power makes it back to be measured for the VSWR measurement. 3- Then there are comments about measuring an *impedance* *at* the load, or 1/2 wavelength away. This is because the *Impedance* repeats every half wavelength in a *LOSS-LESS* line (due to the much discussed physics of waves). For practical lines, with minimal loss, it's pretty close, but, as explained above, approaches 50 ohms (Zo) further and further from the load. Therefore, accuracy in the measured *impedance* degrades further and further >from the load. But/out flag set// 73, Steve, K,9.D;C'I Hi Owen. Article: 222563 of rec.radio.amateur.antenna From: "Steve Nosko" Subject: Re: Skin depth question Date: Mon, 20 Mar 2006 18:40:15 -0600 Message-ID: References: <1142550534.599921.43100@j33g2000cwa.googlegroups.com> <121jsuqafmpqgfb@corp.supernews.com> <121kbb65cj0om31@corp.supernews.com> <121ke06ev9jep86@corp.supernews.com> <121l2g8gk2ep0e4@corp.supernews.com> <1142629987.383332.301360@e56g2000cwe.googlegroups.com> <6adm12pf87ibajc82i7a1hhjh0aivkrpib@4ax.com> "Richard Clark" wrote in message news:6adm12pf87ibajc82i7a1hhjh0aivkrpib@4ax.com... > On 17 Mar 2006 13:13:07 -0800, "art" wrote: > > > Perhaps he has read something that forces the current flow to follow D,C. properties. > > Hmmmm, let's put this another way. Let's say you have a herd of ice > cubes and you put them in a tray of oil. They sink immediately. The > oil is the conductor, and the ice cubes are the charge being > transferred. They sink because of buoyancy. Their weight is greater > than that of the oil so this is our DC metaphor. The ice cubes use > the full depth of the oil. > > Now we create an AC metaphor by replacing the oil with water. The ice > cubes are lighter than water, on a cubic basis, and thus they float. > They cannot use the full depth of the water. The charge has been > forced to the surface to conduct. You can push them underwater, but > once you release them they float again. The water depth that supports > them is the skin of the skin effect. > > Now we create the Skin Effect metaphor. You drain the water to height > that is half that of the ice cubes. The ice cubes now use the full > depth of the water just as they use the full depth of the oil. > However, there is less water than formerly, and less water than > formerly for the oil. The skin depth is not deep enough to support > the charge - resistance increases. > > Oh, and if you wanted penny candy, it would cost 2 cents. One penny > for the candy, and one penny for the 5% tax on the first penny. A > penny doesn't have enough skin depth to support welfare. Richard, This is cute. Both the ice/oil metaphore and the tax round off issue. I think Roy's comment was interpreted as saying that "skin effect does not occur for thin conductors" It was meant that with a thin conductors, the skin effect is there, BUT it is such that you *can consider* the current density as being nearly constant and therefore can be handled by using resistance which will be almost the same as that at DC. Does that do it Roy? 73, Steve, K,9.D;C'I 73, Steve, K,9.D;C'I Article: 222564 of rec.radio.amateur.antenna From: "Steve Nosko" Subject: Re: Skin depth question Date: Mon, 20 Mar 2006 18:54:03 -0600 Message-ID: References: <1142535306.321916.198140@j52g2000cwj.googlegroups.com> <1142542035.975885.202000@z34g2000cwc.googlegroups.com> <1142654608.872051.303460@g10g2000cwb.googlegroups.com> Let me try on this, then I better head for home... "art" wrote in message news:1142654608.872051.303460@g10g2000cwb.googlegroups.com... > Tom, > .....The fact is that I am > refferring to the use of metallised mylar with antennas. Obviously the > metalised thickness could less than any "skin" thicknes. > So one has to decide I can compromise by adding more area to compensate > and by how much. The metal thickness is awfully thin on this material...VERY thin. This means a high resistance. ou should be able to measure what ever you have and see what the DC resistance is. The DC resistance should be the *MINIMUN* you should experience in teh RF domain, right. When you say "adding more area" I think you mean to say that you simply make the Mylar "strip" *Wider*, right. Well, wider means that it'll prpbably have a broader bandwidth also. Now, the key here is whether you can widen it enough to make up for the thin material. I ask if the use of a "strip" of conductor will experience something of a skin-effect-like effect because teh current will tent to force itself out to the edges of teh strip for the same reason skin effect occurs... starte to hurt my brain a this point. I see this as possibly the most effective > change with respect to radiation since we now have forced more current > to the extreme outside surface but this is conjecture on my part. > The answer that is comming back at me is that the current > density is essentially the same but with no explanation > as to why the decay rate has changed since that which creates it has > not changed. > I find it difficult to accept that > the decay rate has changed I don't think it was meant that the decay rate changes. The effect has to still be there. It is that with a thin (compared to skin-depth) conductor, the change in current (density) with depth doesn't change much before you run out of conductor, therefore it can pretty much be ignored. Also, for a round conductor, remember that the decay rate from the two opposite sides will collide with each other. So that it starts to decrease, but half way through it "hits" the other :skin-depth current" and it starts back up again. > and intuatively I would have thought the surface current > would increase significantly. This I don't follow. 73, Steve, K,9.D;C'I Article: 222565 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Skin depth question Date: Mon, 20 Mar 2006 18:06:37 -0800 Message-ID: <121unth8seg6jd0@corp.supernews.com> References: <1142550534.599921.43100@j33g2000cwa.googlegroups.com> <121jsuqafmpqgfb@corp.supernews.com> <121kbb65cj0om31@corp.supernews.com> <121ke06ev9jep86@corp.supernews.com> <121l2g8gk2ep0e4@corp.supernews.com> <1142629987.383332.301360@e56g2000cwe.googlegroups.com> <6adm12pf87ibajc82i7a1hhjh0aivkrpib@4ax.com> Steve Nosko wrote: > > I think Roy's comment was interpreted as saying that "skin effect does not > occur for thin conductors" It was meant that with a thin conductors, the > skin effect is there, BUT it is such that you *can consider* the current > density as being nearly constant and therefore can be handled by using > resistance which will be almost the same as that at DC. > Does that do it Roy? Yes. After art misinterpreted what I originally said (that you can ignore skin effect when the thickness is small enough), I said explicitly just what you did. Maybe it'll sink in a little better after having been said once and explained twice. Roy Lewallen, W7EL Article: 222566 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141772023.638201.196770@j52g2000cwj.googlegroups.com> <2813-441E7292-2246@storefull-3257.bay.webtv.net> <121u2fs34bn1he1@corp.supernews.com> <1142904559.263188.99110@t31g2000cwb.googlegroups.com> Message-ID: Date: Tue, 21 Mar 2006 02:06:23 GMT w8ji@akorn.net wrote: > Can you state in a few clearly written lines what you have learned or > concluded? http://www.qsl.net/w5dxp/current.htm (bottom of page) > 1.) If a loading coil has compact form and is terminated in a > capacitance that presents a reasonably low impedance compared to > inductor capacitance to the outside world, current taper will be > minimal. As a matter of fact, it can be immeasurable. Current taper depends upon where the coil is installed in the standing wave antenna system. It can be flat, positive, or negative. If properly placed, it can even have current flowing into both ends of the coil at the same time, i.e. a 180 degree phase shift in the currents at each end. The coil distorts the current waveform away from the pure cosine envelope presented by a 1/2 wavelength thin-wire dipole but then so does a large diameter conductor. > 2.) Current taper and phase shift do not correspond to the electrical > degrees the loading coil "replaces", except as the physical size of the > loading coil might increase stray capacitance to the outside world. Phase shift corresponds to the delay through the coil. It can be estimated from the self-resonant frequency measurement where the delay is known to be 90 degrees. This is a common method of estimating the delay (electrical length) of a transmission line stub. > 3.) Phase shift of current is anything from zero to a reasonably small > number of degrees, and does not correspond to the electrical degrees > the inductor replaces. My 75m bugcatcher coil occupies about 60 degrees at 4 MHz, 2/3 of the electrical length of the antenna. 60 degrees doesn't seem to meet the definition of "reasonably small". IMHO, that would qualify as "reasonably large", i.e. more than half the electrical length of the 75m mobile antenna. > 4.) There are at least two ways to get a good answer. One is by a > circuit model with enough L and C sections, the other is with a wave > theory approximation. Both models have limits. It is impossible to get a good answer with a model that presupposes faster than light propagation through the coil with equal amplitudes and phases at each end of the coil. The error is the same as assuming such for a piece of transmission line. Dr. Corum's suggested crossover point where the lumped-circuit model fails is 15 degrees or 0.04 of a wavelength. Either the distributed-network model or Maxwell's equations must be used beyond that point in order to obtain valid results. > I think that pretty much is it. What did you conclude? Can you get it > into a few clear words? A 75m bugcatcher coil is a "slow wave structure" described by Ramo and Whinnery, by the IEEE Dictionary, and by Dr. Corum. The velocity factor of my 75m bugcatcher coil has been measured at ~0.017 which agrees with the published formula. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222567 of rec.radio.amateur.antenna From: "David G. Nagel" Subject: Re: SWR Tells Me?? Date: Mon, 20 Mar 2006 20:40:48 -0600 Message-ID: <121uptqb77vn2ce@corp.supernews.com> References: <8P-dnZJZNa_ioYLZ4p2dnA@comcast.com> jimbo wrote: > Allison-nospam@nouce.bellatlantic.net wrote: > >> On Mon, 20 Mar 2006 17:51:28 -0500, Dave wrote: >> >> >>> Bob Miller wrote: >>> >>> SNIPPED >>> >>>> I'm confused, wouldn't it be more important to have the right >>>> impedance and swr at the end of the feedline, where the transceiver is >>>> expecting 50 ohms? >>>> >>>> bob >>>> k5qwg >>>> >>> >>> SNIPPED >>> >>> If you have 50 ohms at the antenna, then you will have 50 ohms >>> regardless of the length of coax. >>> >>> A 3:1 VSWR, assuming other responses to this post are correct, means >>> that your antenna connection could be anything from 16 ohms to 150 >>> ohms and all sorts of combinations of resistance and reactance within >>> that range. >>> >>> An antenna analyzer will let you determine antenna resonance, antenna >>> feedpoint impedance [hopefully 50 ohms], coax line loss, and allow >>> proper adjustment at the connection points for your coax. >>> >>> Once again, find someone in your area with an antenna analyzer. I >>> repeat my offer if you are within 60 +/- miles of Concord NH. >> >> >> >> >> It's possible to tune a Jpole with just a SWR meter. I've done ti >> many times though it's more tedious than with an antenna analyser. >> >> The simplest step is add some length to the long section, not alot >> and see how the change affects it. Add more or less as needed >> for a good minimum. If the minimum is still not on the mark (1:1 >> is ideal but anything under 1.3:1 flies well) then adjust the tap >> point (very small movements) and resweep again. With patience >> you (the person that asked) will get it right. >> >> What happens with Jpoles is they often are not built identical >> and small differences do show. Also like most halfwave and >> larger antennas being close to "stuff" tends to affect tuning. >> No harm or foul but learning to prune (aka tune) an atenna is a skill >> and worth developing. >> >> Allison >> KB1GMX > > > Adding some length to the long leg would be relatively easy, BUT moving > the feed point would be a real challenge! The coax shield and center > conductor are soldered to the ladder line wires. When I tuned a j-pole > in my work shop, tiny movements made a change amd maintaining the > position while trying to get it soldered was nearly impossible. (At > least for my clumsy fingers.) Is there a better way to connect the feed > point? > > Thanks, jimbo Connect your feed points to the Jpole using clamps. Adjust the location of the feed point and the characteristic impedance by moving the clamps. You do not have to adjust the length of the feed line until you fine tune the feed point impedance. I just finished making the collapsible jpole antenna that was featured in QST last spring. When I first tested the impedance it was way off. All I had to do was loosen the clamps and bump the clamps up and down the pole to obtain optimal settings. Due to the out of ham band use I will be putting the jpole to the SWR at my xmit freq. is higher than I would like the midpoint SWR is about 1.1:1. This is why Antenna design is an ART not a SCIENCE. Dave WD9BDZ Article: 222568 of rec.radio.amateur.antenna From: "Bill Turner" Subject: Re: vert vs dipole gut comparison References: <1142897819.468971.52560@i40g2000cwc.googlegroups.com> <86HTf.3411$tN3.1493@newssvr27.news.prodigy.net> <1iHTf.3414$tN3.2471@newssvr27.news.prodigy.net> Message-ID: <441f6ce5$1_4@newsfeed.slurp.net> Date: 20 Mar 2006 22:03:01 -0500 ORIGINAL MESSAGE: Cecil Moore wrote: > Cecil Moore wrote: > > fazamy@aol.com wrote: > > >> Is the polarity of the sending station and receiving station > > relevant > >> to this discussion?? > > > Yes on ground wave VHF/UHF. No on HF skip. > > Oops, lest some nitpicker jump in, I should have said "surface > wave", not "ground wave". And I probably should have included > a "usually" while I was at it. > -- *********** REPLY SEPARATOR *********** Nitpicker alert: 1. You should have not limited the "NO" to HF. Six meters is also a "NO" for ionospheric skip. 2. Polarity of the signal for ground wave (not surface or space wave) is indeed important. Vertical polarization works best. Horizontal is rapidly attenuated. Bill, W6WRT Article: 222569 of rec.radio.amateur.antenna From: Tom Uwano Subject: Re: Antenna Height? Date: Tue, 21 Mar 2006 12:12:56 +0900 Message-ID: References: <1142885660.257565.164800@i40g2000cwc.googlegroups.com> Dan Andersson wrote: > Ron J wrote: > >> Hello and greetings all, >> >> I borrowed a field strength measurement equipment from the school lab. >> I wanted to measure the the field strength of a low power FM >> transmitter. I was told that I need to setup the antenna height >> correctly. I didn't think of this. I thought all I need is the proper >> antenna length and polarization for measurement. Can anyone give me >> some insight regarding using the proper antenna height? Thank you. > So there are no simple answer to your question Ron, not without more > information. > Cheers > Dan / M0DFI Generally when you place TX and RX antennas above the ground and you change the height of RX antena, you see the variation of signal strength. This is due to the ground reflection and we call it "height pattern." Probably your manual suggests this influence. How to avoid this? (although both methods do not give rigorous results,) 1. You may take the average of height patten. 2. Make the distance short between the antennas. Tom/jj3fbs Article: 222570 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <%Y3Tf.584343$qk4.104946@bgtnsc05-news.ops.worldnet.att.net> <121pmm3758jm4f4@corp.supernews.com> <8kqp12h5hs3bmrn2vn34i96m5fr0osv90s@4ax.com> <121q4fbgb89gb1a@corp.supernews.com> <121qh4dm7om8j13@corp.supernews.com> <1142813624.391779.279150@t31g2000cwb.googlegroups.com> <1142814316.040782.285000@i39g2000cwa.googlegroups.com> <1142822862.985006.247970@t31g2000cwb.googlegroups.com> <2upTf.185$wg6.164@fe10.lga> <1142850891.475736.293910@v46g2000cwv.googlegroups.com> <1142903394.663573.26510@v46g2000cwv.googlegroups.com> Subject: Re: Current through coils Message-ID: Date: Mon, 20 Mar 2006 22:35:54 -0500 > OK, so you have no theory and I assume no opinion. > Good enough. > 73 Tom > That just about summarizes you. You don't need theory, just go measure it as I described. The theory started with Dr. Nikola Tesla and skillfully defended by W5DXP. I don't claim to steal anybody's theory, other people came up with explanation of the effect, I am just defending it based on reality, burned coils and not coming up with "theory" that would back up wrong claims. What the hell is all the discussion about? Your misinformation on your web site, and you can't allow to get it right, because you can't possibly be wrong or admit to it. Just crap, no answer to technical questions, defending your baloney. What's your theory? RF behaves like DC in a loading coil? ANSWER the frickin questions!!! You can't, because you either don't get it or your ego doesn't allow you to get it. Pretty sad picture. I have no more to say, if you have no answers. I get better response from a brick wall. Just don't claim to be engineer or "JI Engineering". Engineers do not behave like that, they have certain code of ethics and rules on usage of term engineer and engineering. You might want to check with Georgia Engineers association. I am sorry about all this, but I just don't take a crap and for the umpteen time, it just gets too much. Man who attacked misinformation on Interned on QRZ pages is guilty of the same. K7GCO has a name for people like that: "Technical imposters". Sayonara!! Yuri, K3BU Article: 222571 of rec.radio.amateur.antenna From: "Sal M. Onella" References: Subject: Re: vert vs dipole gut comparison Message-ID: Date: Mon, 20 Mar 2006 20:07:08 -0800 "Gary Schafer" wrote in message news:qmjt12143asea3dkefhi3v1lpucoh86pbh@4ax.com... > > > > > > You want both antennas if you can do it. Anyone who declares one or the > >other the winner is simply wrong. > > > > - 73 de Mike KB3EIA - > > I did some tests a couple of years ago on 10 meters between vertical > and horizontal on an 1800 mile path. It seems that there is quite a > bit of rotation in polarity of the signal from minute to minute. I > tried right and left hand circular to confirm that it was rotation. > > 73 > Gary K4FMX > Cross-polarization losses are in the neighborhood of 10-20 dB at VHF and above. With my license, I cannot do HF, so others may chime in with those numbers. Assuming ... there's that word ... that the random polarization variations ("rotations") are around some central figure, during for a given QSO, then one antenna will work better -- the one that happens to be optimum for that path and for the antenna on the other end of the QSO. There exists a phenomenon that I do not understand well, called Faraday rotation, where an EM wave passing through a magnetic field will undergo a polarization "alteration", so to speak. Thus, two verticals on the ends of a long-distance QSO might not perform as well as if one were a vertical and the other a horizontal -- due to the Earth's magnetic field. John KD6VKW Article: 222572 of rec.radio.amateur.antenna From: "Mike Coombes" References: <1141772023.638201.196770@j52g2000cwj.googlegroups.com> <2813-441E7292-2246@storefull-3257.bay.webtv.net> <121u2fs34bn1he1@corp.supernews.com> <1142904559.263188.99110@t31g2000cwb.googlegroups.com> <1142936775.983229.257760@j33g2000cwa.googlegroups.com> Subject: Re: Current through coils Date: Tue, 21 Mar 2006 18:46:55 +0800 Message-ID: <441fd9a1$0$4671$5a62ac22@per-qv1-newsreader-01.iinet.net.au> Grow up. wrote in message news:1142936775.983229.257760@j33g2000cwa.googlegroups.com... > > Cecil Moore wrote: >> w8ji@akorn.net wrote: >> > Can you state in a few clearly written lines what you have learned or >> > concluded? >> >> http://www.qsl.net/w5dxp/current.htm (bottom of page) > > > Thanks Cecil. I wanted to be sure where you were at now. > We still disagree about several important points. > > In a few more years, there might be a resolution. > > 73 Tom > Article: 222573 of rec.radio.amateur.antenna From: Allison-nospam@nouce.bellatlantic.net Subject: Re: SWR Tells Me?? Message-ID: References: <8P-dnZJZNa_ioYLZ4p2dnA@comcast.com> Date: Tue, 21 Mar 2006 13:20:20 GMT On Mon, 20 Mar 2006 16:36:39 -0700, jimbo wrote: >Allison-nospam@nouce.bellatlantic.net wrote: >> What happens with Jpoles is they often are not built identical >> and small differences do show. Also like most halfwave and >> larger antennas being close to "stuff" tends to affect tuning. >> No harm or foul but learning to prune (aka tune) an atenna is >> a skill and worth developing. >> >> Allison >> KB1GMX > >Adding some length to the long leg would be relatively easy, BUT >moving the feed point would be a real challenge! The coax shield and >center conductor are soldered to the ladder line wires. When I tuned a >j-pole in my work shop, tiny movements made a change amd maintaining >the position while trying to get it soldered was nearly impossible. >(At least for my clumsy fingers.) Is there a better way to connect the >feed point? > >Thanks, jimbo Welcome to practical antenna building. There is no easy way. What I've done is loosely wrap the coax leads around the ladder line so they can be slid up or down. If the spot is wrong a bit of heat and slide the wires and try again. I've seen lugs that have set screws used for high power connections used as well but they may or may not weather well and once you set those to the correct tap point you will find any tape applied to seal them alters things. Generally I've found ladder line Jpoles and twinlead Jpole to be the fussiest as any change in the insulator or wire diameter affects tuning. The small diameter wire makes for narrow bandwidth. They do work as well as the larger pipe versions when tuned. Due to insulator variations from vendor to vendor the antenna has a bad rep for reproducability. That aside when I got the first one right, every one built using material from the same roll was identical. Thay are light and flexible but can be frustrating. When I need a Jpole a copper pipe one of known design (one I've built before) copied absolutely always behaves the same. The 1/2" pipe versions offer better SWR bandwidth than wire. That greater bandwidth also makes tuning less narrow and fussy. The most critical dimension is the gap between the parallel sections, the second most is the tap point and the overall lengths are usually easiest to insure are accurate. At VHF (2m) small changes(less than .5%) in dimensions or other properties are significant in any antenna. That applies to diameter of material, spacings, and any insulators including a changes in the type of insulating material. The more elaborate the antenna (Jpole, Moxon, Beam, or whatever) the more noticeable the effect. For 2m antenna builders I advise a 1/4 wave groundplane as first antenna. If they want more gain or a more robust antenna a copper pipe Jpole does well. The latter is easier as all the items are big and it is easiest to control dimensions accurately. For the purists, a balun (current type) should be used. I've found a coiled section of feed line worked fine. I've also set up in the field with no baluns and if the antenna is properly tuned and matched (tap point) the performance is unimpaired by the lack of balun. There are designs (Arrow OSJ series) that do not require a balun as they use an end fed open stub rather than shorted stub. Allison Article: 222574 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141772023.638201.196770@j52g2000cwj.googlegroups.com> <2813-441E7292-2246@storefull-3257.bay.webtv.net> <121u2fs34bn1he1@corp.supernews.com> <1142904559.263188.99110@t31g2000cwb.googlegroups.com> <1142936775.983229.257760@j33g2000cwa.googlegroups.com> Message-ID: Date: Tue, 21 Mar 2006 13:31:23 GMT w8ji@akorn.net wrote: > Thanks Cecil. I wanted to be sure where you were at now. > We still disagree about several important points. "The unwillingness of the "gurus" to answer specific technical questions is pretty disappointing." - a comment from a reader. You said you could use the lumped-circuit model to explain how the current at the top of the coil could be greater than the current at the bottom of the coil as it is at the bottom of the page at: http://www.qsl.net/w5dxp/current.htm If you are technically correct, why are you so technically silent on the subject? Does the emperor have no clothes? At least a dozen of my technical questions have gone unanswered by being ignored. Lot's of readers have noticed and commented in emails to me. If you will repeat your measurements with 1/4WL added to the top of the base-loaded mobile antenna, you will start to understand the physics involved. The current taper through a coil depends upon where in the standing wave environment that the coil is installed. The lumped-circuit analysis fails for the typical 75m amateur radio mobile antenna. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222575 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: SWR Tells Me?? References: Message-ID: Date: Tue, 21 Mar 2006 14:05:38 GMT jimbo wrote: > Thanks for all of the advice. I have one more question. Can I tune a > J-Pole antenna in my shop and then move it to the attic and expect the > same performance? In other words, is an antenna an antenna or is an > antenna and it's installation an antenna? You can tune a J-Pole antenna at one place in free space, move it to another place in free space, and expect the same results. The real world is not so forgiving. The conditions will not be identical but they may (or may not) be close enough to be acceptable to you. Welcome to the real world of ham radio. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222576 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141772023.638201.196770@j52g2000cwj.googlegroups.com> <2813-441E7292-2246@storefull-3257.bay.webtv.net> <121u2fs34bn1he1@corp.supernews.com> <1142904559.263188.99110@t31g2000cwb.googlegroups.com> <1142936775.983229.257760@j33g2000cwa.googlegroups.com> <1142949872.509816.132830@i40g2000cwc.googlegroups.com> Message-ID: Date: Tue, 21 Mar 2006 14:47:43 GMT w8ji@akorn.net wrote: > Cecil Moore wrote: >>If you are technically correct, why are you so technically >>silent on the subject? > > I'm not silent. You are silent on the subject of how the lumped-circuit model explains more current at the top of the coil than exists at the bottom of the coil. Please share that knowledge with us. > I think I've done a good job of explaining things, and I've made > measurements and posted results. Have you made measurements with 1/4WL added to the top of a mobile antenna? Will you believe your measurements when you measure more current "flowing" into the bottom of the coil than out of the top of the coil? >>At least a dozen of my technical questions have gone >>unanswered by being ignored. Lot's of readers have >>noticed and commented in emails to me. > > So what? :-) > 1.) I told you weeks ago I'm too busy working right now to get deeply > involved in this. :-) > 2.) When measurements are made, you dismiss them as "measuring current > in a system with standing waves". It has been proven beyond a reasonable doubt that standing wave current, func(kx)*func(wt) is not like traveling wave current, func(kx +/- wt). Since standing wave current phase is devoid of phase information, its phase cannot be used to determine the phase shift through a coil. Standing wave current phase is what W7EL measured. He drew conclusions about phase from measuring the phase of a signal devoid of any phase information. I pointed that technical fact out to him at the time and he ignored me. I also pointed out that the phase information was actually embedded in the amplitude measurement as a variation of a cosine function. He rejected that assertion with a personal remark. >>If you will repeat your measurements with 1/4WL added >>to the top of the base-loaded mobile antenna, you will >>start to understand the physics involved. The current >>taper through a coil depends upon where in the standing >>wave environment that the coil is installed. > > Then why can I measure a fixed inductor location in a dfixed antenna, > and range from no taper at all in current to just under 1/3 reduction > in current? Does you standing wave model explain this very repeatable > measurement? Of course! If you measure the current taper at a point where the standing wave current slope is near zero, you will measure near zero taper. If you measure the current taper at a point where the standing wave current slope is near maximum, you will measure lots of taper. If you measure at just the right point, you will measure current flowing into both ends of the coil at the same time. That's another thing I have asked you to explain with no response. >>The lumped-circuit analysis fails for the typical >>75m amateur radio mobile antenna. > > I disagree. Unless we want to say so does the standing wave model. The "standing wave model" is a component of the distributed-network model which is known to work in the presence of standing waves. The lumped-circuit model is known to fail in the presence of standing waves. Quoting Dr. Corum: "There are no standing waves on a lumped element circuit component. (In fact, lumped-element circuit theory inherently employs the cosmological presupposition that the speed of light is infinite, as every EE sophmore should know. See, e.g., - "Electric Circuits", by J.W.Nilsson, Addison-Wesley, 1983, p. 3." Dr. Corum's first sentence above means: *There are no standing waves *allowed* in a lumped element circuit model.* > The antenna can be modelled as a series of lumped inductors with > capacitance to the outside world just as well as any other method. But that is not what you and W7EL have done. You have modelled it as a single coil with distributed capacitance. That approach is known to fail when the coil is longer than 15 degrees and installed in a standing wave environment. If you use enough lumped inductors and capacitors, you have the distributed network model but with a lot more math to do. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222577 of rec.radio.amateur.antenna From: Gene Fuller Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <28826-441C4099-1651@storefull-3255.bay.webtv.net> <121ojih732ucf6f@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> Message-ID: <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> Date: Tue, 21 Mar 2006 15:09:57 GMT Hi Tom, You may be shocked to discover this, but it is possible that my comments have been reproduced slightly out of context. At the time, Cecil was still clinging to the notion that if someone did the measurements properly they could elicit the original phase information contained in the traveling wave components. In particular, the space and time coupling represented by the traveling wave function, cos (kz - wt), was merely hiding. He has since changed his mind, and unfortunately I seem to have become one of his quotable gurus on this topic. A major part of the ongoing debate is the careless use of "phase" as if it has a single definition. I have counted at least five different uses in this thread, all correct in their own way, and none interchangeable. I won't try to explain further. My level of understanding of phase and such matters is fully satisfactory for me. 73, Gene W4SZ Tom Donaly wrote: > Cecil Moore wrote: >> >> Gene is 100% correct and we all should be grateful for that posting. >> >> Neither you nor Roy have ever made a valid measurement of the >> delay through a coil. It is admittedly a difficult measurement >> to make directly. Ramo and Whinnery say it "is usually of >> prohibitive difficulty". > > > I think that if Gene believes that, he should redo his math. > 73, > Tom Donaly, KA6RUH Article: 222578 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <28826-441C4099-1651@storefull-3255.bay.webtv.net> <121ojih732ucf6f@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> Message-ID: Date: Tue, 21 Mar 2006 15:32:26 GMT Gene Fuller wrote: > At the time, Cecil was still clinging to the notion that if someone did > the measurements properly they could elicit the original phase > information contained in the traveling wave components. Sorry, Gene, you misunderstood what I was saying. That's why you accidentally posted technical information that supported my side of the argument without realizing it at the time. (Remember, I said you were a genius for posting it and I thank you.) What I previously said was: If the reflected wave could be eliminated, as in a traveling wave antenna (like a terminated Rhombic) then we could measure the actual delay through a loading coil using the forward traveling wave, the only wave left in the system. Here's one leg of a terminated Rhombic: source-------------////////------------------load coil When I said the delay through a coil could be measured using a traveling wave, this is what I had in mind. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222579 of rec.radio.amateur.antenna From: Gene Fuller Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <28826-441C4099-1651@storefull-3255.bay.webtv.net> <121ojih732ucf6f@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> Message-ID: Date: Tue, 21 Mar 2006 16:00:07 GMT Cecil, Sorry, I am not telepathic. I merely accepted you at your written word, which appears to be of little worth. 73, Gene W4SZ Cecil Moore wrote: > Gene Fuller wrote: > >> At the time, Cecil was still clinging to the notion that if someone >> did the measurements properly they could elicit the original phase >> information contained in the traveling wave components. > > > Sorry, Gene, you misunderstood what I was saying. That's why you > accidentally posted technical information that supported my side > of the argument without realizing it at the time. (Remember, I said > you were a genius for posting it and I thank you.) > > What I previously said was: If the reflected wave could be eliminated, > as in a traveling wave antenna (like a terminated Rhombic) then > we could measure the actual delay through a loading coil using > the forward traveling wave, the only wave left in the system. > > Here's one leg of a terminated Rhombic: > > source-------------////////------------------load > coil > > When I said the delay through a coil could be measured using a > traveling wave, this is what I had in mind. Article: 222580 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <28826-441C4099-1651@storefull-3255.bay.webtv.net> <121ojih732ucf6f@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> Message-ID: Date: Tue, 21 Mar 2006 16:50:41 GMT Gene Fuller wrote: > Sorry, I am not telepathic. I merely accepted you at your written word, > which appears to be of little worth. I am often thinking faster than I can type and wind up not expressing myself very well. This time, your misunderstanding worked out to my advantage because it prompted you to post some technical facts in rebuttal to what you assumed I said. Your and Tom Donaly's technical facts were instrumental in getting my point across and I thank you both for that. You two seem to be the only ones posting who understand the physics implication of func(kx)*func(wt) Vs func(kx +/- wt). Thanks again. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222581 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Current through coils Date: Tue, 21 Mar 2006 10:58:25 -0600 Message-ID: <18781-442030B1-2232@storefull-3252.bay.webtv.net> References: <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> Gene, W4SZ wrote: "A major part of the ongoing debate is careless use of "phase" as if it has a single definition." If Gene has counted at least five different uses in this thread, what are they? Phase is defined as 1) The angular relationship between current and voltage in alternating-current (a-c) circuits. 2) The number of separate voltage waves in a commercial a-c supply such as single-phase, three-phase, etc. 3) The time that has elapsed measured from some origin as a frection of one complete period of a periodic function. I don`t think the problem in the debate is that the participants don`t know the circumference of a circle is 2 pi radians or 360-degrees, or that 360-degrees equals a complete period or one wavelength. The problem is that some participants don`t admit their mistakes and hope they are unnoticed or can be hidden by plenty of nonsense. J.J. Rousseau swore to consecrate his life to the truth. So did Lucy Ball, but she recommended fibbing about one`s age. It is hard to keep a vow to be truthful but it is good for the environment. Too many here struggle for status by hook or crook and fib when the truth would work better. Best regards, Richard Harrison, KB5WZI Article: 222582 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: i need help References: <1142962151.940082.139270@i40g2000cwc.googlegroups.com> Message-ID: Date: Tue, 21 Mar 2006 17:36:23 GMT zabad wrote: > am seth and a new member to this group, what i want is to create my > own vt antenna but have no ideal on it. am asking if you can help me > solve this. What are the limitations and specifications that the antenna must meet? -- 73, Cecil http://www.qsl.net/w5dxp Article: 222583 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <28826-441C4099-1651@storefull-3255.bay.webtv.net> <121ojih732ucf6f@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> Message-ID: Date: Tue, 21 Mar 2006 19:39:09 GMT Gene Fuller wrote: > Hi Tom, > > You may be shocked to discover this, but it is possible that my comments > have been reproduced slightly out of context. > > At the time, Cecil was still clinging to the notion that if someone did > the measurements properly they could elicit the original phase > information contained in the traveling wave components. In particular, > the space and time coupling represented by the traveling wave function, > cos (kz - wt), was merely hiding. He has since changed his mind, and > unfortunately I seem to have become one of his quotable gurus on this > topic. > > A major part of the ongoing debate is the careless use of "phase" as if > it has a single definition. I have counted at least five different uses > in this thread, all correct in their own way, and none interchangeable. > > I won't try to explain further. My level of understanding of phase and > such matters is fully satisfactory for me. > > 73, > Gene > W4SZ > > Tom Donaly wrote: > >> Cecil Moore wrote: > > >>> >>> Gene is 100% correct and we all should be grateful for that posting. >>> >>> Neither you nor Roy have ever made a valid measurement of the >>> delay through a coil. It is admittedly a difficult measurement >>> to make directly. Ramo and Whinnery say it "is usually of >>> prohibitive difficulty". >> >> >> >> I think that if Gene believes that, he should redo his math. >> 73, >> Tom Donaly, KA6RUH You're right, Gene, I'm shocked! shocked! to learn that Cecil might distort anything anyone might write. I never for a moment, though, thought there was anything wrong with your understanding. It was Cecil's understanding of your understanding that was in doubt. 73, Tom Donaly, KA6RUH Article: 222584 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <28826-441C4099-1651@storefull-3255.bay.webtv.net> <121ojih732ucf6f@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> Message-ID: Date: Tue, 21 Mar 2006 20:53:30 GMT Cecil Moore wrote: > Tom Donaly wrote: > >> I never for a moment, though, thought there was anything wrong with >> your understanding. > > > Tom, are you retracting what you posted? If so, just come right out > and say so. Otherwise, you are going to have to live with the reality > that what you posted agrees with my side of the argument and disagrees > with W8JI and W7EL. Both of you guys say there is no phase information > left in the measured phase of the standing wave current. Do you wish > to retract your statements? Since W7EL measured the phase of the > standing wave current and drew illogical conclusions from that > measurement, are you guys going to support W7EL's conclusion or > support the technical facts that you posted previously? Please choose. > > Seems to me you are caught between supporting the irrationality of > a friend or the laws of physics. Please choose the technically > correct side. Ham Radio will be better served by that decision. Cecil, the cork has popped. You've finally succumbed to fantasy and solipsism to the point where your reason has failed utterly. There must be something in Texas that addles the intellect. I urge you to go climb in your old pickup, Roxinante, and drive the hell out of there. (And remember to remove the Tom Delay bumper sticker when you cross the border into Oklahoma.) Maybe, given time, you'll recover some of your understanding. 73, Tom Donaly, KA6RUH Article: 222585 of rec.radio.amateur.antenna From: "Stargatesg1" References: <1142976206.750445.110100@t31g2000cwb.googlegroups.com> Subject: Re: Dual rhombic antenna Message-ID: Date: Tue, 21 Mar 2006 21:53:57 GMT Also I would check to make sure the gain is listed as 26 DBd instead of DBi. Back in the day, allot of companies inflated their specs by stating the DBi gain instead of DBd. DBi being gain over an isotropic and DBd being gain over a dipole. -- RoD KD0XX PG-6-29404 "Richard Clark" wrote in message news:s2s022lrmb8o93pcgelj94l4jvpgh8u4qb@4ax.com... > On 21 Mar 2006 13:23:26 -0800, tucker@conninc.com wrote: > > >The claims > >for > >this antenna seem streached abit, they claim 26dB gain from just wire > >and a few resistors > >and claim its 435mhz design can work up to 890mhz, theres even a quad > >rhombic shown > >also. Sounds to good to be true, so i wandering if anyone has had any > >experience with > >actually building & using one of these antennas. I would like to build > >some kind of high gain recieve > > only antenna to see if its possible to get a decent signal from some > >of the ATV repeaters. > > Hi OM, > > It's as good as any other.... Good being highly qualified, especially > as the construction details are so shy of description here. Barring > those details, rhombics are not a mystery. > > If it works on the 440 Band, you can scale it down for the 900 band if > you want it shorter, or just use the instructions provided. How good > it performs remains to be tested. You would have to test anyway to > confirm any antenna claim for gain. > > 73's > Richard Clark, KB7QHC Article: 222586 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <28826-441C4099-1651@storefull-3255.bay.webtv.net> <121ojih732ucf6f@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> Message-ID: Date: Tue, 21 Mar 2006 21:53:24 GMT Tom Donaly wrote: > Cecil, the cork has popped. You've finally succumbed to fantasy and > solipsism to the point where your reason has failed utterly. > There must be something in Texas that addles the intellect. I urge you > to go climb in your old pickup, Roxinante, and drive the hell out of > there. (And remember to remove the Tom Delay bumper sticker when you > cross the border into Oklahoma.) Maybe, given time, you'll recover some > of your understanding. The technical content of your postings supports my side of the argument, Tom. The emotional side of your argument seems to support the other side. Which do you want us to believe? -- 73, Cecil http://www.qsl.net/w5dxp Article: 222587 of rec.radio.amateur.antenna Subject: Re: OLD 5 BAND TRP ANTENNA From: Tom P Randall KB2SMS References: <441c880a$0$7604$afc38c87@news.optusnet.com.au> <7qednZwzx5xX5oDZnZ2dnUVZ_sOdnZ2d@comcast.com> Date: 21 Mar 2006 22:06:02 GMT Message-ID: <442078ca$0$9579$6d36acad@titian.nntpserver.com> "gb" wrote in news:7qednZwzx5xX5oDZnZ2dnUVZ_sOdnZ2d@comcast.com: >> A good photos would help .. > Like this? http://i1.tinypic.com/rwi885.jpg *** Free account sponsored by SecureIX.com *** *** Encrypt your Internet usage with a free VPN account from http://www.SecureIX.com *** Article: 222588 of rec.radio.amateur.antenna From: "David G. Nagel" Subject: Re: Dual rhombic antenna Date: Tue, 21 Mar 2006 16:34:12 -0600 Message-ID: <1220vrc6h9tqece@corp.supernews.com> References: <1142976206.750445.110100@t31g2000cwb.googlegroups.com> Stargatesg1 wrote: > Also I would check to make sure the gain is listed as 26 DBd instead of DBi. > Back in the day, allot of companies inflated their specs by stating the > DBi gain instead of DBd. > DBi being gain over an isotropic and DBd being gain over a dipole. > At 26Db there isn't enough difference between dipole and isotropic to matter. Dave WD9BDZ Article: 222589 of rec.radio.amateur.antenna From: David Subject: Reading SWR with low power Message-ID: Date: Tue, 21 Mar 2006 22:45:37 GMT Hi, What would anyone recommend for measuring SWR on a system that has a low power transmitter (20mW) ? My meter has lowest range of 3W FSD. I do have a digital power meter and directional coupler, would it be best to manually measure fwd power and reverse pwr and calculate SWR ? Thanks in Advance Regards David Article: 222590 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Dual rhombic antenna Date: Tue, 21 Mar 2006 14:50:50 -0800 Message-ID: <12210qejjsk1k4b@corp.supernews.com> References: <1142976206.750445.110100@t31g2000cwb.googlegroups.com> <1220vrc6h9tqece@corp.supernews.com> To get 26 dB over a dipole would require rhombic leg lengths of about 125 wavelengths, or about 275 feet at 450 MHz. The overall length would be around 500 feet. The beamwidth would be so narrow you'd have difficulty getting it aimed toward one station, even if you were able to turn it somehow. Roy Lewallen, W7EL David G. Nagel wrote: > Stargatesg1 wrote: >> Also I would check to make sure the gain is listed as 26 DBd instead >> of DBi. >> Back in the day, allot of companies inflated their specs by >> stating the >> DBi gain instead of DBd. >> DBi being gain over an isotropic and DBd being gain over a dipole. >> > At 26Db there isn't enough difference between dipole and isotropic to > matter. > > Dave WD9BDZ Article: 222591 of rec.radio.amateur.antenna From: Gene Fuller Subject: Re: Current through coils References: <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <18781-442030B1-2232@storefull-3252.bay.webtv.net> Message-ID: Date: Tue, 21 Mar 2006 23:06:52 GMT Hi Richard, I am not going to spend any more time on this topic, but I will answer the "5 phase" question. I am not going to try for extreme precision, so I suspect the nit-pickers will have a field day. 1. The classic relationship between current and voltage in a reactive environment. 2. The time and space connection in a traveling wave, the "kz-wt" term. 3. The amplitude shape factor in a standing wave, the "kz" term. 4. Fixed offsets that effectively show different starting times for waves. For example, "kz-wt" vs. "kz-wt-d". 5. The sign reversal every half-wave on a long antenna. This is merely a reflection of the periodic nature of a cosine function, but it is often called a "phase reversal". There are more, I am sure, but these are the ones that I specifically saw in the first 1000 or so postings in this thread. 73, Gene W4SZ Richard Harrison wrote: > Gene, W4SZ wrote: > "A major part of the ongoing debate is careless use of "phase" as if it > has a single definition." > > If Gene has counted at least five different uses in this thread, what > are they? > > Phase is defined as 1) The angular relationship between current and > voltage in alternating-current (a-c) circuits. 2) The number of separate > voltage waves in a commercial a-c supply such as single-phase, > three-phase, etc. 3) The time that has elapsed measured from some origin > as a frection of one complete period of a periodic function. > > I don`t think the problem in the debate is that the participants don`t > know the circumference of a circle is 2 pi radians or 360-degrees, or > that 360-degrees equals a complete period or one wavelength. > > The problem is that some participants don`t admit their mistakes and > hope they are unnoticed or can be hidden by plenty of nonsense. J.J. > Rousseau swore to consecrate his life to the truth. So did Lucy Ball, > but she recommended fibbing about one`s age. It is hard to keep a vow to > be truthful but it is good for the environment. > > Too many here struggle for status by hook or crook and fib when the > truth would work better. > > Best regards, Richard Harrison, KB5WZI > Article: 222592 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <28826-441C4099-1651@storefull-3255.bay.webtv.net> <121ojih732ucf6f@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> Message-ID: <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> Date: Tue, 21 Mar 2006 23:48:19 GMT Cecil Moore wrote: > Tom Donaly wrote: > >> Cecil, the cork has popped. You've finally succumbed to fantasy and >> solipsism to the point where your reason has failed utterly. >> There must be something in Texas that addles the intellect. I urge you >> to go climb in your old pickup, Roxinante, and drive the hell out of >> there. (And remember to remove the Tom Delay bumper sticker when you >> cross the border into Oklahoma.) Maybe, given time, you'll recover >> some of your understanding. > > > The technical content of your postings supports my side of the > argument, Tom. The emotional side of your argument seems to > support the other side. Which do you want us to believe? Cecil, this reminds me of an old Groucho line that goes something like, "Who are you going to believe, me or what you see with your own eyes?" You're expecting me to believe what you thought up in your head over what Tom Rauch and Roy saw with their own eyes. This whole thing boils down to an engineering question, anyway, which is, is it possible to engineer a loading coil to be small enough at the lower end of the HF spectrum so that it can be modeled using network analysis? Tom says he can do it, and he's posted the results of his research efforts on the web. He hasn't had to rely on sophistry, selective quotations, huge numbers of irrational posts, threats, unproven theories, or anything other than numbers derived through carefully done experimentation to make his point. When you can do likewise, Cecil, you won't have to act like a lunatic to make your point, the numbers will do it for you, and the rest of us will be spared the spectacle of watching you defending, with your last breath, something you aren't willing to take the time to even fully understand. 73, Tom Donaly, KA6RUH Article: 222593 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Reading SWR with low power Date: Tue, 21 Mar 2006 23:58:35 +0000 (UTC) Message-ID: References: "Cecil Moore" wrote in message news:g30Uf.62109$dW3.27078@newssvr21.news.prodigy.com... > David wrote: > > My meter has lowest range of 3W FSD. I do have a digital power meter and > > directional coupler, would it be best to manually measure fwd power and > > reverse pwr and calculate SWR ? > > On the upstream side of the diodes (if any) in the directional > coupler, you might be able to obtain AC measurements proportional > to the forward and reflected power, depending upon the sensitivity > of your meter. It could also be done using an o'scope. > -- > 73, Cecil http://www.qsl.net/w5dxp =========================================== And having found SWR what would he do with it - calculate forward and reflected power ? ;o) ;o) ;o) ;o) ;o) ;o) ;o) ;o) ;o) ;o) ;o) ;o) ;o) ;o) ;o) ;o) ;o) ;o) ;o) ;o) Article: 222594 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: Dual rhombic antenna References: <1142976206.750445.110100@t31g2000cwb.googlegroups.com> Message-ID: Date: Tue, 21 Mar 2006 18:04:34 -0600 This gain figure sounds very much like the 144MMz EME double rhombic that was in the ARRL handbook for years. As I remember it was "attacked" some years ago for claiming such a high gain. I built one for 70cm some years ago and the results were disappointing, or rather not as good as a 22 el loop quad. I didnt do much experimenting with it sorry. Cheers Bob VK2YQA tucker@conninc.com wrote: > > I picked up a Oct 1973 issue of 73 & noticed a interesting article on > a mast mounted rotatible very Article: 222595 of rec.radio.amateur.antenna From: David Subject: Re: Reading SWR with low power References: Message-ID: Date: Wed, 22 Mar 2006 00:11:57 GMT I suppose then I then should just measure forward power from the incident port and then tune the antenna while monitoring power on the reflected port (of the directional coupler) for min. reflected power. I should have also mentioned frequency is 900 MHz. Article: 222596 of rec.radio.amateur.antenna From: "Dale Parfitt" References: Subject: Re: Quad Antenna Message-ID: Date: Wed, 22 Mar 2006 00:28:04 GMT "Howard W3CQH" wrote in message news:zPGdnR_G5aU_Cr3ZRVn-gA@adelphia.com... > Question - Is the polarity of the antenna based on the feed point? > > 73's >Yes Article: 222597 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: New Program. Transmission Line Transformers. Date: Wed, 22 Mar 2006 00:33:17 +0000 (UTC) Message-ID: There are two transmission lines in cascade plus a load impedance. The first line can be considered to be the main line from the transmitter. The second line can be considered to be an impedance matching transformer between the first line and the antenna. What is the impedance and length of line in the transformer if the antenna feedpoint impedance is not purely resistive? What are the input impedances of the two lines, R+jX ? What percentage of transmitter power is dissipated in the two lines? What is the overall power efficiency? The answers can be found in new program TWOLINES. SWR is not involved. Download program TWOLINES from website below in a few seconds and run immediately. -- ........................................................... Regards from Reg, G4FGQ For Free Radio Design Software go to http://www.btinternet.com/~g4fgq.regp ........................................................... Article: 222598 of rec.radio.amateur.antenna From: "Caveat Lector" References: Subject: Re: Quad Antenna Message-ID: Date: Tue, 21 Mar 2006 16:47:31 -0800 "Howard W3CQH" wrote in message news:zPGdnR_G5aU_Cr3ZRVn-gA@adelphia.com... > Question - Is the polarity of the antenna based on the feed point? > > 73's > Yes -- see URL: http://www.ham-shack.com/beam.html -- CL -- I doubt, therefore I might be ! Article: 222599 of rec.radio.amateur.antenna From: "Jerry Martes" References: <1142976206.750445.110100@t31g2000cwb.googlegroups.com> Subject: Re: Dual rhombic antenna Message-ID: <0h2Uf.13289$bu.3519@trnddc04> Date: Wed, 22 Mar 2006 02:04:44 GMT wrote in message news:1142976206.750445.110100@t31g2000cwb.googlegroups.com... > I picked up a Oct 1973 issue of 73 & noticed a interesting article on > a mast mounted rotatible very > hig gain 435mhz antenna, cheap and easy to built. Ive been trying to > build a high gain antenna to > recieve ATV in the 903-928 band & seems this maybe the one. The claims > for > this antenna seem streached abit, they claim 26dB gain from just wire > and a few resistors > and claim its 435mhz design can work up to 890mhz, theres even a quad > rhombic shown > also. Sounds to good to be true, so i wandering if anyone has had any > experience with > actually building & using one of these antennas. I would like to build > some kind of high gain recieve > only antenna to see if its possible to get a decent signal from some > of the ATV repeaters. > Seems here in western N.C. the ATV activity is located mostly in this > located band. > Thx N4aeq Hi Tucker I had to re-look at the month that article was published to be sure it wasnt an April 1 issue. The antenna's beamwidth, with a circular cross section, will be close to 10 degrees maximum. It is likely that a 12 foot diameter dish would be the minimum size that would provide that 26 dB Gain at 900 MHz. That gets pretty difficult to make stable when also rotateable. I would suggest that you start with a Yagi and try it. You'll soon know if that gain is adequate. And the money spent on parts wont hurt your pocketbook. I sure wouldnt expect you to jump into antenna design with a beginning project of building a 26 dB Gain rotateable antenna. Jerry Article: 222600 of rec.radio.amateur.antenna From: kb9rqz@mark_morgan.com Subject: Re: OLD 5 BAND TRP ANTENNA Date: Tue, 21 Mar 2006 17:12:19 -0500 Message-ID: References: <441c880a$0$7604$afc38c87@news.optusnet.com.au> <7qednZwzx5xX5oDZnZ2dnUVZ_sOdnZ2d@comcast.com> <442078ca$0$9579$6d36acad@titian.nntpserver.com> On 21 Mar 2006 22:06:02 GMT, Tom P Randall KB2SMS wrote: >"gb" wrote in >news:7qednZwzx5xX5oDZnZ2dnUVZ_sOdnZ2d@comcast.com: > >>> A good photos would help .. >> >Like this? > >http://i1.tinypic.com/rwi885.jpg > WTF? All I see is a pic of a slob! _________________________________________ Usenet Zone Free Binaries Usenet Server More than 140,000 groups Unlimited download http://www.usenetzone.com to open account Article: 222601 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: Dual rhombic antenna References: <1142976206.750445.110100@t31g2000cwb.googlegroups.com> <1142992552.184809.168690@i40g2000cwc.googlegroups.com> Message-ID: <0kp6f3-1mq.ln1@p400bob.personal.cox.net> Date: Tue, 21 Mar 2006 20:33:03 -0600 Scaling shouldnt be an issue so start by looking at 1296MHz antennas. You can always computer model them as well. Have a look at Mr Cebiks' website. (http://www.cebik.com) I'd actually recommend you look at a corner reflector. Nowhere as critical as a yagi and pretty easy to build. Maybe even a 3D corner? I've been wanting to try a Sterba curtain (on 900mHz) over a planar reflector. That wouldnt be real critical either. Cheers Bob Vk2YQA tucker@conninc.com wrote: > > Exactly what i wanted to know, i may hold off on this one and search > for a different type high gain uhf antenna. Only problem is all > the design programs i have found on the web for yagi or log perodic > antennas are for 6-8 elements maximum, @ 900mhz i would like to have > as many elements as a boom would support. So my next question would be > where to look for a multi element beam using atleast a minimum of > twelve elements? > Article: 222602 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: Quad Antenna References: Message-ID: <6qp6f3-1mq.ln1@p400bob.personal.cox.net> Date: Tue, 21 Mar 2006 20:36:22 -0600 Yes! Feeding at the "bottom" makes it horizontal and the "side" vertical. There is obviously some response in the other polarity (more than a yagi?) but I havent researched this. The square can also be a rectangle... (Beware of feedpoint Z changes) You can also feed the in quadrature on two adjacent corners for circular.. Cheers Bob VK2YQA Howard W3CQH wrote: > Question - Is the polarity of the antenna based on the feed point? > > 73's > > Article: 222603 of rec.radio.amateur.antenna From: "Leadfoot" Subject: building a yagi Message-ID: Date: Wed, 22 Mar 2006 03:27:09 GMT I going to build a 11 element yagi but the problem I'm having is I can't find the aluminum rods, I was wondering if I use copper if I will still get the same Db gain. I was thinking of another metal was to use brake line from a car that I can get in the auto parts store. Thanks Ledfoot Article: 222604 of rec.radio.amateur.antenna From: "Sal M. Onella" References: Subject: Re: SWR Tells Me?? Message-ID: Date: Tue, 21 Mar 2006 22:15:22 -0800 "jimbo" wrote in message news:RZadnXHuHeVRmb3Z4p2dnA@comcast.com... > jimbo wrote: > > > Thanks for all of the advice. I have one more question. Can I tune a > J-Pole antenna in my shop and then move it to the attic and expect the > same performance? In other words, is an antenna an antenna or is an > antenna and it's installation an antenna? > > It would seem to me that if the antenna is tuned and works in my shop > it should work in the attic. Otherwise, how do "store bought" antennas > work? > > Thanks, jimbo I have built about twenty copper-pipe j-poles and I have found that with five feet or so between the antenna and surroundings, the tuning doesn't change enough to be annoying. The copper pipe j-pole can be dropped into a pipe and hoisted into the clear for VSWR evaluations if you really want to get gnats-assey about it. Speaking of that, I have found that j-poles usually don't hit 1:1, even when the low point is mid-band. However, after I get the best match, I insert a 100 pF capacitor between the coax center pin and the antenna and "Viola!" I stole that idea from the gamma match. Article: 222605 of rec.radio.amateur.antenna From: "Richard Miller" References: <441c880a$0$7604$afc38c87@news.optusnet.com.au> <7qednZwzx5xX5oDZnZ2dnUVZ_sOdnZ2d@comcast.com> <442078ca$0$9579$6d36acad@titian.nntpserver.com> Subject: Re: OLD 5 BAND TRP ANTENNA Date: Wed, 22 Mar 2006 17:44:15 +1100 Message-ID: <4420f248$0$20115$afc38c87@news.optusnet.com.au> I have not posted the photos of the antenna yep -- Regards, Richard Miller E-mail: wizzard6@optusnet.com.au wrote in message news:ugu0229sumptf07ceqcqvi5mbi6q5e8fl4@4ax.com... > On 21 Mar 2006 22:06:02 GMT, Tom P Randall KB2SMS > wrote: > >>"gb" wrote in >>news:7qednZwzx5xX5oDZnZ2dnUVZ_sOdnZ2d@comcast.com: >> >>>> A good photos would help .. >>> >>Like this? >> >>http://i1.tinypic.com/rwi885.jpg > >> > WTF? All I see is a pic of a slob! > _________________________________________ > Usenet Zone Free Binaries Usenet Server > More than 140,000 groups > Unlimited download > http://www.usenetzone.com to open account Article: 222606 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Current through coils Date: Wed, 22 Mar 2006 01:11:10 -0800 Message-ID: <122255j5m0eed84@corp.supernews.com> References: <121mh75g3ekkme9@corp.supernews.com> <28826-441C4099-1651@storefull-3255.bay.webtv.net> <121ojih732ucf6f@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> Ian White GM3SEK wrote: > . . . > In principle there is nothing wrong with attempting a traveling-wave > analysis for a loaded whip. Done correctly, it will give the right > results that join up seamlessly with circuit theory as well. > . . . One of the tests the traveling wave analysis must pass is that the results from forward current wave excitation plus the results from reverse current wave excitation must equal the results from excitation by the sum of the two, i.e., the total current. This is required by superposition, whether the network is lumped or distributed. And analysis based on a distributed model, as Ian says, must converge to the same results as a model with lumped components as the physical sizes of the components get very small. Analyses of the examples using lumped models with total current have been entirely adequate to explain the observed inductor currents. Roy Lewallen, W7EL Article: 222607 of rec.radio.amateur.antenna From: Deni Subject: Balloon lifted wire antenna? Date: Wed, 22 Mar 2006 10:36:48 +0100 Message-ID: I'm going to have a go with a 3/8 wavelength (for 160M) wire, lifted by a 2M helium balloon during the summer months. The first 40' of wire will be supported vertically by a fibre glass mast then the remaining 156' by the balloon. I have a ground plane in place already and will use a manual tuner at the base to 50 ohm coax, I expect to use this on other bands besides Top band. What is a good type of wire to use, obviously flexible, not too heavy but good copper content, or would electric fence cord (with woven in stainless steel strands) be too lossy? looking for any tips advice etc. 73, Deni F5VJC Article: 222608 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Reading SWR with low power Date: Wed, 22 Mar 2006 10:48:57 +0000 (UTC) Message-ID: References: > I should have also mentioned frequency is 900 MHz. ========================================= About time too! It could have all been happening on 160 meters. ;o) Article: 222609 of rec.radio.amateur.antenna From: Allison-nospam@nouce.bellatlantic.net Subject: Re: SWR Tells Me?? Message-ID: <0df222l7igln084ed4hs1ohte1u5sukspr@4ax.com> References: Date: Wed, 22 Mar 2006 12:09:52 GMT On Tue, 21 Mar 2006 22:15:22 -0800, "Sal M. Onella" wrote: > >"jimbo" wrote in message >news:RZadnXHuHeVRmb3Z4p2dnA@comcast.com... >> jimbo wrote: >> >> >> Thanks for all of the advice. I have one more question. Can I tune a >> J-Pole antenna in my shop and then move it to the attic and expect the >> same performance? In other words, is an antenna an antenna or is an >> antenna and it's installation an antenna? >> >> It would seem to me that if the antenna is tuned and works in my shop >> it should work in the attic. Otherwise, how do "store bought" antennas >> work? >> >> Thanks, jimbo > >I have built about twenty copper-pipe j-poles and I have found that with >five feet or so between the antenna and surroundings, the tuning doesn't >change enough to be annoying. > >The copper pipe j-pole can be dropped into a pipe and hoisted into the clear >for VSWR evaluations if you really want to get gnats-assey about it. I've found getting them 6ft (for 2m ) above the ground was enough that another 20ft didn't change it enough to measure. >Speaking of that, I have found that j-poles usually don't hit 1:1, even >when the low point is mid-band. However, after I get the best match, >I insert a 100 pF capacitor between the coax center pin and the antenna >and "Viola!" I stole that idea from the gamma match. > I've had good swr match(1:1 or unmeasurably close) without the cap. Also the original poster has the ladder line based jpole in the attic. If it's like most I've seen the attic is within 5ft . Like I'd said elsewhere the twinlead and ladder line versions are fussier and tend to be different from one batch of wire to another. Allison Article: 222610 of rec.radio.amateur.antenna From: Tom Uwano Subject: Re: Antenna Height? Date: Wed, 22 Mar 2006 21:09:42 +0900 Message-ID: References: <1142885660.257565.164800@i40g2000cwc.googlegroups.com> <1142993322.516980.173120@z34g2000cwc.googlegroups.com> > Tom, can you clarify on how to take the average height of the pattern? It is not the average height. It is the average reception power. Suppose you change the height of RX antenna (preferably together with TX antenna) by (more than) a half wave length, you'll observe maximum level Px and minimum level Pn. So the reception voltages Vx and Vm are sqrt(Px) and sqrt(Pm). The average voltage Va is then (Vx+Vm)/2. Thus average RX power is Va^2. > Also, if I keep the TX and RX antenna close, wouldn't that eliminate > the far-field effects? It is not a far-field measurement. But the error might not be as much as 3dB if the distance is such as two to three wave-lengths, which is sometimes better than the bad average measurement performance or doing nothing. Tom/jj3fbs Article: 222611 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <28826-441C4099-1651@storefull-3255.bay.webtv.net> <121ojih732ucf6f@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> Message-ID: Date: Wed, 22 Mar 2006 12:51:41 GMT Ian White GM3SEK wrote: To all: Ian is not addressing the issue which is: Can a standing wave current phase measurement be used to tell us anything about the phase shift through a loading coil? The answer is NO! W7EL's phase measurements are flawed. Therefore, they cannot be presented as evidence of anything valid. They certainly cannot be used to prove that a coil is a point inductance. The question is not whether the two models agree on the low end - they do agree. The question is whether they agree on the high end - they don't and they are not supposed to. The differences I have presented in the two models is where the lumped circuit model fails and the distributed network model is valid. > There is an infinite range of real-life loading coils of various shapes > and sizes. Pure single-point inductive loading is the limiting case that > marks one end of that range. Any successful theory has GOT to get this > case right - and if it can't, it fails. Since the distributed network model is a superset of the lumped circuit model, it does get that case right. It also gets the case right at the other end of the range where the lumped circuit model fails. 75m mobile loading coils cannot be validly modeled using the lumped circuit model. > Regardless of the actual method used, any correct analysis of the whole > antenna MUST conclude that, for the limiting case of pure inductive > loading, the voltage/current/phase relationships at the loading > inductance are the SAME as those predicted by conventional circuit > analysis. This limiting case is where the two kinds of analysis come > together, and here they MUST agree. And they do, no question about that. > That means a correct analysis for the whole antenna MUST predict zero > phase shift in the current (It = I0 cos wt) between the terminals of the > loading inductance. Here you are allowing your model to dictate reality, not vice versa. A practical antenna is a large structure, usually at least an electrical 1/4 wavelength. There is no such thing as a point inductance in a real world mobile ham antenna. > Let's be clear: in this context, "current" is the plain ordinary > alternating current that we learned about in school: It = I0 cos wt. It > is the simple back-and-forth movement of electrons (charge) past a given > point. Let's be clear. That model fails in a transmission line as it does in standing wave antennas. Taking a simple-minded approach to physics is where the air, earth, fire, and water elements came from. > Nobody denies that for real-life loading coils there can be a phase > shift in the current from end to end, and that it will become larger as > the coil becomes longer and skinnier. That isn't the question I'm > addressing here. But the question of what happens when the coil shrinks > down to become a single-point loading inductance is equally important: > it cannot be evaded, and it is a definitive deal-breaker. In that case, both models give the same answer. But that case doesn't exist in reality in real-world antennas. In reality, the lumped circuit model fails when it is extended to large structures like transmission lines and antennas. > It's hard to tell for sure from the avalanche of messages, but Cecil's > analysis apparently fails in the limiting case of pure inductance - or > rather, he seems to deny that the test is even a valid one. The distributed network analysis works perfectly in the limiting case since it is a superset of the lumped circuit model. There is absolutely no disagreement between the distributed network analysis and the lumped circuit analysis for point inductors. Anyone who says there is is just attempting to set up a strawman. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222612 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <28826-441C4099-1651@storefull-3255.bay.webtv.net> <121ojih732ucf6f@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <122255j5m0eed84@corp.supernews.com> Message-ID: <0SbUf.41014$_S7.40340@newssvr14.news.prodigy.com> Date: Wed, 22 Mar 2006 12:58:36 GMT Roy Lewallen wrote: > One of the tests the traveling wave analysis must pass is that the > results from forward current wave excitation plus the results from > reverse current wave excitation must equal the results from excitation > by the sum of the two, i.e., the total current. This is required by > superposition, whether the network is lumped or distributed. It certainly does that within the bounds of the principle of superposition. But as I earlier pointed out, like two superposed PSK modem signals, phase information is lost in the superposition. You used standing wave current phase to try to measure the phase shift through a coil. Your attempt was futile since the standing wave current phase doesn't contain any phase information. > And analysis based on a distributed model, as Ian says, must converge to > the same results as a model with lumped components as the physical sizes > of the components get very small. And it certainly does. But the distributed network model works for antennas and transmission lines where the lumped circuit model fails. The lumped circuit model is supposed to fail for transmission lines and antennas. > Analyses of the examples using lumped models with total current have > been entirely adequate to explain the observed inductor currents. Maybe for you, Roy, but not for me and others. Are the four elements of earth, air, water, and fire adequate to explain the physical world to your satisfaction? -- 73, Cecil http://www.qsl.net/w5dxp Article: 222613 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121ojih732ucf6f@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <122255j5m0eed84@corp.supernews.com> <1143019485.927955.293220@t31g2000cwb.googlegroups.com> Message-ID: Date: Wed, 22 Mar 2006 13:08:37 GMT w8ji@akorn.net wrote: > Cecil claims I'm the ONLY one who disagrees with him! False! Gene Fuller, Tom Donaly, and Roy Lewallen have all made postings that support my side of the argument against yours. That doesn't mean they agree with me 100%. They agree with me on some technical things that are not in dispute except by you. 1. Standing wave current, Func(kz)*Func(wt), is a different thing >from traveling wave current, Func(kz +/- wt). The phase of standing wave current contains zero phase information and therefore cannot be used to ascertain anything about phase. Roy's phase measurements were meaningless and his conclusions were flawed. 2. The EZNEC results need to be explained by you guys. When you accused my measurements of being wrong, Roy reported that EZNEC agrees with my measurements. How do you explain that? 3. How do you explain the EZNEC results on my web page at: http://www.qsl.net/w5dxp/current.htm All of the arm-waving in the world is not going to make these technical facts go away. I will be leaving for spring break tomorrow morning and won't be back until Sunday night. It would be nice for you guys to have answered my 12 or so technical questions by then. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222614 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121ojih732ucf6f@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <122255j5m0eed84@corp.supernews.com> <1143019485.927955.293220@t31g2000cwb.googlegroups.com> <$ubYHlOF5TIEFAPM@ifwtech.co.uk> Message-ID: Date: Wed, 22 Mar 2006 13:40:25 GMT Ian White GM3SEK wrote: > The only thing those people have in common is a desire to get the facts > right... I have asked you guys to explain the technical facts behind about a dozen technical questions of mine. The silence has been deafening. Many readers of this newsgroup have noticed the same thing. Here are the technical facts about the two models. At one end of the spectrum, we have lumped inductance. At the other end we have physically huge coils. The crossover point where the lumped circuit model becomes invalid is about 0.04 wavelength. A mobile antenna is a lot longer than that. At lengths above, 0.04 wavelength, standing waves have to be taken into account. The lumped inductance model cannot take standing waves into account. It assumes instantaneous faster-than-light propagation of current. DC|-------------distributed network model valid----------------| DC|---lumped circuit model valid---| 0.04WL cutoff Here are the two main technical points: 1. Nothing valid is proven by using standing wave current phase to measure anything. Gene F. and Tom D. seem to realize that. 2. The taper of the standing wave current through a coil depends upon where the coil is placed in the standing wave environment. You guys have looked only at mobile antennas. Try looking at longer antennas like the one at: http://www.qsl.net/w5dxp/current.htm You will find that the current taper through a coil can be zero, positive, negative, or even reverse phase. The phase reversal can be considered to be current flowing into both ends of the coil at the same time. Please come out of the deep dark lumped circuit cave and see what the rest of the world is like. You guys have been seduced by your model. You have assumed the presuppositions of the model are valid without technical proof. Here's an analogy: Ian W. says: I believe water is one of the basic elements and as proof, I offer a quart of water. Roy L. says: I believe earth is one of the basic elements and as proof, I offer a bucket of earth. Tom R. says: I believe fire is one of the basic elements and as proof, I offer this burning torch. Richard C. says: I believe air is one of the basic elements and as proof, I offer this balloon full of it. Cecil says: I believe there are over 100 elements and as proof, I offer this periodic chart of those elements. I will be on spring break until Monday so don't think I have given up on getting the technical facts out there for all to see. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222615 of rec.radio.amateur.antenna From: Gene Fuller Subject: Re: Current through coils References: <121ojih732ucf6f@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <122255j5m0eed84@corp.supernews.com> <1143019485.927955.293220@t31g2000cwb.googlegroups.com> Message-ID: Date: Wed, 22 Mar 2006 13:41:53 GMT Cecil, Sorry, Ian had it exactly correct. I cannot speak for Roy or others, but I am quite sure I did not take any "side" in this topic. I believe in lumped circuit models, and I believe in network models. My aim was to try to correct some of the basic math and physics flaws, not to argue over the exact regimes of applicability for lumped and non-lumped models. If you choose to use my postings as support for your "side", so be it. At the same time, if proving your "side" includes mobile antennas with 48 foot whips and giant bugcatcher coils working at three times their self-resonant frequency, then please leave me off of your "side". 73, Gene W4SZ Cecil Moore wrote: > w8ji@akorn.net wrote: > >> Cecil claims I'm the ONLY one who disagrees with him! > > > False! Gene Fuller, Tom Donaly, and Roy Lewallen have all made > postings that support my side of the argument against yours. > That doesn't mean they agree with me 100%. They agree with me > on some technical things that are not in dispute except by you. Article: 222616 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121ojih732ucf6f@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <122255j5m0eed84@corp.supernews.com> <1143019485.927955.293220@t31g2000cwb.googlegroups.com> Message-ID: Date: Wed, 22 Mar 2006 14:06:45 GMT Gene Fuller wrote: > I am quite sure I did not take any "side" in this topic. I assume you are on the side of technical facts as am I. > I believe in > lumped circuit models, and I believe in network models. My aim was to > try to correct some of the basic math and physics flaws, not to argue > over the exact regimes of applicability for lumped and non-lumped models. Your func(kx)*func(wt) Vs func(kx +/- wt) posting contributed a good deal of technical accuracy to the discussion and I thank you for that. > At the same time, if proving your "side" includes mobile antennas with > 48 foot whips ... then please leave me off of your "side". And there's the blind spot. The two antennas are identical except for the 40 foot extension. The coil doesn't know the extension is there. Why did the slope of the current taper reverse between those two configurations? How does the lumped-circuit model explain more current "flowing" out of the top of the coil than is "flowing" into the bottom of the coil? It's a simple question but the answer has been conspicuous by its absence. I will keep asking that question until someone answers it. The distributed network analysis handles both of those configurations in a valid way. Adding 40 feet to an antenna is no problem. The relative phases of the forward and reflected currents changed - that's all that happened. But by adding 40 feet of wire to the antenna, the lumped circuit analysis falls completely apart. So how do we know it was valid for the 8 foot antenna where everything is the same except for length? We don't! Since the lumped circuit analysis falls apart by adding 40 feet to an antenna, I contend that the lumped circuit analysis fell apart with the 8 foot antenna but you guys don't realize it yet. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222617 of rec.radio.amateur.antenna From: Michael Coslo Subject: Re: First Attempt Date: Wed, 22 Mar 2006 09:16:40 -0500 Message-ID: References: Old Ed wrote: > Hi Michael, > > Thank you for your comments! I'd be interested in trading experiences > with you on the OCF topic, either here or direct. Did you make one > or buy one? I made mine. The design is a combination of one of the antennas on the salsawaves site. (I don't have the URL handy, but if you google salsawaves it will get you there.) The other section of the design was with EZNEC demo. > I have interleaved some other responses below... > > 73, Ed > > "Michael Coslo" wrote in message > news:dvmot3$1nle$1@f04n12.cac.psu.edu... >> Old Ed wrote: >>> Reg, >>> >>> The type of antenna you describe is very useful and popular. >>> >>> However, your assertion is much too sweeping as a generalization. >>> In no particular order, here are some caveats: >>> 1. The qualifier "best" is largely meaningless, absent an agreed >>> set of weighted criteria for "goodness." (How important is: >>> size? weight? cost? visual profile? bandwidth? instant QSY? >>> gain? pattern? low-band performance vs. high-band performance? >>> power-handling capacity? need for tuner? etc., etc., etc.) >> I'm always hesitant to use words like "best" for all the reasons you >> state, but I think that Reg qualified things pretty well. > > I think Reg's ONLY qualifiers were "all round, all band" (presumably > meaning 80 thru 10). To me, that description falls well short of the > mark, as "qualifiers." > >> Within the >> qualifications of all band dipoles, the ladder-line fed general dipole >> is pretty darn hard to beat. I recommend them to any new hams that ask >> me for advice on antennas. >> > You can make a good case for this proposition. But I'm a bit puzzled > on how these qualify as A-1 newbie antennas. > > First, our newbie to learn how to coddle finicky ladder line, bring it > into the shack, and make the transition to unbalanced feed. Then he/she > needs a crash course on transmatches: > 1. Balanced or unbalanced design? (If unbalanced, may not work well > with this antenna; if balanced, may not work with future, coax-fed > antennas.) > 2. Low or high power? (If low, may need to upgrade later.) > 3. Manual or automatic? (If automatic, how interface to rig?) > 4. Which brand and model? (Might Fine Junk or $quality$?) > 5. New or used? > 6. How do you operate the transmatch? I've always suggested cutting teeth on low power, then working your way up. Mistakes are a lot less dangerous that way. In most cases, I suggest the MFJ approach. I have one that is now in a emergency backup. My thoughts on them are that they are certainly not the highest quality, but they work, and you can always get rid of one to start another ham on their way. > If our newbie wants some power-handling capability, and plans > to buy it new, he/she will need an extra 500 to 700 USD and more > space on the desk. > > Re Reg's reference to a choke balun: I've been looking for good quality, > commercial choke baluns equipped with SO-239 inputs and outputs. > So far, I haven't found any; and I haven't been quite motivated enough > to make one. What should our newbie do to get one, if needed? I've made all my baluns, 4:1 and choke, for my setup. But you raise a good point, as I'll note below. >> My rationale is that most new hams these days buy rigs that are >> all-band, transistorized units.These units are also sensitive to >> mismatches between antenna and rig. Most new hams are not antenna gurus >> either. So here is an antenna that will allow them to get on the air >> without a lot of fussing. The only real measurement caveats are some >> lengths that you don't want to use. >> > I can't quite see how slogging thru all the above is going to be easier for > a newbie than buying a Buckmaster OCF or basic trap dipole, buying a > ready-made coax jumper of the required length, and then doing plug- > and-play with the (typical) rig's built-in auto-tuner. But it probably > would be more educational. Ah, Ed, you have exposed me being shortsighted! I'm a compulsive homebrewer, and I never considered buying a ready made antenna. The other approach might be quite different than mine, and yet just as valid. > >> So we end up with an antenna that allows the newbie to get on the air, >> allows them to learn some stuff by twiddling knobs and such, then when >> they have a bit more experience, they can tackle that more "advanced >> antenna" with it's more exacting design, trimming , and measurements. >> > I'm having a hard time figuring out what antenna type(s) would be "more > advanced" than the random-length-doublet-with-outboard-ATU, and > yet require more fiddling. If a person decides to make a trap or even more so a fan dipole, they will be doing a lot of cutting and trimming and measuring. I've always thought that for a newbie to get their feet wet, the less of that and the more on-air experience with adjustments the better. > But I will grant you this: IF someone decides from the get-go that they > want a glitzy transmatch at their operating position--whether they need > it or not--then the balanced-feeder doublet makes pretty good sense. > This would be especially true if there wasn't enough space for something > like a Buckmaster OCF, but there was enough space for (say) an 88' > doublet. I've made an 88" doublet for field day. It was a very good antenna on 20 and 40 meters, and so-so on 80.(still not too awful bad). I know someone is going to ask me to define "Very good". In this case, I received many unsolicited comments on good signal strength on 40 and 20, had no trouble getting through on first call. On 80 I had to work a good bit harder. It is good to get another perspective on this. - 73 de Mike KB3EIA - - >> >>> 2. A good case can be made that choosing the "right" length is >>> "better" than a random length, within this type. >>> 3. An excellent case can be made that center-fed is NOT always >>> the "best" option, within this type. >>> 4. I'll let the fans of this antenna type chime in with why they >>> prefer balanced tuners and/or tuned feeders to the use of an >>> unbalanced tuner... if they want to. (I use more tailored > antennas, >>> and don't need a tuner of any kind, most of the time.) >> As I do now. I've really been smitten with my OCF dipole, fed with >> Coax, because in no small part, the feedpoint drops straight down to my >> shack. That coupled with an automatic tuner in my radio , allowing me to >> "plug and play. >> >> But I still strongly urge newcomers to put up one of those ladder line >> dipoles for the experience. They work okay, too! 8^) >> >>> "Reg Edwards" wrote in message >>> news:dvhp20$ap9$1@nwrdmz01.dmz.ncs.ea.ibs-infra.bt.com... >>>> The best, all round, all band, antenna is a high centre-fed dipole of >>>> no particular length, fed with an open-wire feedline of no particular >>>> length or impedance, all the way to the shack, used with a choke-balun >>>> and an unbalanced tuner. >>>> >>>> It is good down to the frequency at which the dipole is about >>>> 1/3-wavelength long. >>>> >>>> Simplicity = efficiency. >>>> >>>> Once tried you will never return to anything else. >>>> ---- >>>> Reg. >>>> >>>> >>> > > > Article: 222618 of rec.radio.amateur.antenna From: Butch Magee Subject: Wideband Folded Loop Construction Details Date: Wed, 22 Mar 2006 08:32:40 -0600 Message-ID: <1222o0f8rbouha3@corp.supernews.com> Geltlemen, I have been considering the Wideband Folded Loop (WFL) for a couple of weeks now to use as a secondary antenna when talking with all of the local yocals who are spread out on 40 and 75 and 80 mtrs. I have seen the photographs of the assembled antenna, BUT, no dimentions and by reducing the physicical size of the antenna, I'm guessing the multiple dimentions must be pretty tight to function as a no tuner 1.5 to 30 mHz. Any help would be greatly appreciated. Thanks Butch KF5DE Article: 222619 of rec.radio.amateur.antenna From: Bob Miller Subject: Re: Reading SWR with low power Message-ID: References: Date: Wed, 22 Mar 2006 14:35:05 GMT On Wed, 22 Mar 2006 10:48:57 +0000 (UTC), "Reg Edwards" wrote: >> I should have also mentioned frequency is 900 MHz. >========================================= > >About time too! It could have all been happening on 160 meters. ;o) > I was going to recommend my Oakhills Research qrp wattmeter; it has a 100 milliwatt scale, but it is only rated to 54 mhz. I also looked at the Bird list of slugs -- they have 100 milliwatt slugs, but not in the 900 mhz range. bob k5qwg Article: 222620 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <28826-441C4099-1651@storefull-3255.bay.webtv.net> <121ojih732ucf6f@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> Message-ID: Date: Wed, 22 Mar 2006 14:39:07 GMT Ian White GM3SEK wrote: > I flatly do not accept your notion of a special kind of "standing wave > current" that has its own special kind of phase properties. We already know that, Ian. Please drag out your dusty math book and try to understand the difference between the standing wave current function, func(kx)*func(wt), and the traveling wave current function, func(kx +/- wt). They are obviously different. Calling the standing wave current a "current" is something of a misnomer since it doesn't exhibit the characteristics of a normal current at all. What are the implications of a "fixed phase" for a current, i.e. its phasor doesn't rotate? Do you disagree with Gene's technically accurate posting on the subject? ***************************************************************************** > Gene Fuller, W4SZ wrote: >> In a standing wave antenna problem, such as the one you describe, there is no >> remaining phase information. Any specific phase characteristics of the traveling >> waves died out when the startup transients died out. >> >> Phase is gone. Kaput. Vanished. Cannot be recovered. Never to be seen again. >> >> The only "phase" remaining is the cos (kz) term, which is really an amplitude >> description, not a phase. The so-called "phase reversal" in longer antennas is >> not really about phase either. It is merely a representation of the periodic >> sign reversal seen in a cosine function. ****************************************************************************** > The current that the loading coil experiences is plain old ordinary > alternating current flowing in the wire ... False! Standing wave current is different from DC, AC, or RF traveling waves. Please take time out to understand the implications of a non-rotating phasor for a current. All other AC currents have rotating phasors but the standing wave current phasor doesn't rotate all up and down a 1/2WL thin-wire dipole. That makes it extremely different from any other AC current. > Any special kind of current that requires electronic components to > behave in some different way from normal is simply not real. The forward current and the reflected current are not special. The superposed standing wave current doesn't behave as normal current at all. It's phase doesn't change along the entire length of a 1/2WL thin- wire dipole. I have said this a dozen times and it hasn't yet soaked in yet so I will continue to repeat it. What does unchanging phase imply about a standing wave current? All other AC currents change phase. > You have a fundamental misconception of what a standing wave of current > really is. You repeat all the words about "standing waves", "cos kz", > "scientific logic", "laws of physics" etc; but you don't actually let > any of it into your mind. I am open-minded, Ian, and use the scientific method to correct my mistakes and thus zero in on the technical facts. One of a guru's presuppositions is that he already knows everything. I have no such misconceptions about myself. > All the questions you ask other people are rooted in your own > misconceptions. In other words, the questions are rigged so that they > cannot be answered except by agreeing with you. No, Ian, my questions are rigged so they cannot be answered except by agreeing with the laws of physics and gurus cannot afford to show their ignorance of the laws of physics. That leaves them between a rock and a hard place as far as answering my questions are concerned. That's the only reason for the "Silence of the Gurus". -- 73, Cecil http://www.qsl.net/w5dxp Article: 222621 of rec.radio.amateur.antenna From: Bob Miller Subject: Re: SWR Tells Me?? Message-ID: References: <0df222l7igln084ed4hs1ohte1u5sukspr@4ax.com> Date: Wed, 22 Mar 2006 14:43:05 GMT On Wed, 22 Mar 2006 06:22:12 -0700, jimbo wrote: >Allison-nospam@nouce.bellatlantic.net wrote: >> On Tue, 21 Mar 2006 22:15:22 -0800, "Sal M. Onella" >> wrote: >> >> >>>"jimbo" wrote in message >>>news:RZadnXHuHeVRmb3Z4p2dnA@comcast.com... >>> >>>>jimbo wrote: >>>> >>>> >>>>Thanks for all of the advice. I have one more question. Can I tune a >>>>J-Pole antenna in my shop and then move it to the attic and expect the >>>>same performance? In other words, is an antenna an antenna or is an >>>>antenna and it's installation an antenna? >>>> >>>>It would seem to me that if the antenna is tuned and works in my shop >>>>it should work in the attic. Otherwise, how do "store bought" antennas >>>>work? >>>> >>>>Thanks, jimbo >>> >>>I have built about twenty copper-pipe j-poles and I have found that with >>>five feet or so between the antenna and surroundings, the tuning doesn't >>>change enough to be annoying. >>> >>>The copper pipe j-pole can be dropped into a pipe and hoisted into the clear >>>for VSWR evaluations if you really want to get gnats-assey about it. >> >> >> I've found getting them 6ft (for 2m ) above the ground was enough that >> another 20ft didn't change it enough to measure. >> >> >>>Speaking of that, I have found that j-poles usually don't hit 1:1, even >>>when the low point is mid-band. However, after I get the best match, >>>I insert a 100 pF capacitor between the coax center pin and the antenna >>>and "Viola!" I stole that idea from the gamma match. >>> >> >> I've had good swr match(1:1 or unmeasurably close) without the cap. >> >> Also the original poster has the ladder line based jpole in the attic. >> If it's like most I've seen the attic is within 5ft . Like I'd said >> elsewhere the twinlead and ladder line versions are fussier and >> tend to be different from one batch of wire to another. >> >> >> Allison > >Yes, the attic has the roof within five feet. No walls but lots of >cross braces. I am going to tune a J-Pole in my shop and then take it >to the attic and check the difference. > >jimbo I have a ladderline j-pole right outside my attic, in a small tree, and I lucked out on swr, just following the measurements I found on the internet diagram of the thing. One trick you might try is to stick a straight pin into the insulation, touching the longer wire element. Raise and lower the pin for resonance. bob k5qwg Article: 222622 of rec.radio.amateur.antenna From: John Ferrell Subject: Re: Dual rhombic antenna Message-ID: <3tq2225udqrak72ng16fit5qjiubc9eljt@4ax.com> References: <1142976206.750445.110100@t31g2000cwb.googlegroups.com> <1143035643.588010.282750@z34g2000cwc.googlegroups.com> Date: Wed, 22 Mar 2006 15:31:33 GMT I thought it sounded familiar. I have not kept in touch the last decade but Bill was a mentor to me. He did a lot of antenna experimenting, especially on 432 mhz. He is listed in QRZ.Com, you might send him a snail mail. As I recall, the article was written during the building of the antenna. Testing after the article was published did not support the calculations. Unfortunately you cannot "un publish" a hard copy! Most of us were still using slide rules & calculators to crunch number then! On 22 Mar 2006 05:54:03 -0800, tucker@conninc.com wrote: > No Jerry its August 1977 - 73 magizine, im looking at it now & they >try and compare all other antennas to it and noe even come close. The >article was writen by Bill Parker W8dmr, anyway i think i will stay >with a yagi type or try ands build a 8 bay biquad like the Channel >Master uhf tv antenna. > >N4aeq John Ferrell W8CCW Article: 222623 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: Wideband Folded Loop Construction Details References: <1222o0f8rbouha3@corp.supernews.com> Message-ID: <1d88f3-52s.ln1@p400bob.personal.cox.net> Date: Wed, 22 Mar 2006 09:51:27 -0600 Hi Butch Are you talking about the terminated folded dipole antenna? Mr Cebik has a rundown on them at; http://www.cebik.com/wire/wbfd.html and says that the antenna is "typically" 90ft long for 80-10m. There is however a non trivial loss at 80m you may want to check on. If you like "no tuner" also consider Cecils w5dxp's doublet at; http://www.qsl.net/w5dxp/notuner.htm That uses sections of 450 ohm feedline that are swicthed in and out of circuit. Cheers Bob W5/VK2YQA Butch Magee wrote: > > > Geltlemen, > I have been considering the Wideband Folded Loop (WFL) Article: 222624 of rec.radio.amateur.antenna From: Cecil Moore Subject: "Silence of the Gurus" Message-ID: Date: Wed, 22 Mar 2006 16:22:32 GMT It's spring break time and I won't be back until Monday. On my web page at http://www.qsl.net/w5dxp/current.htm - is what EZNEC says about a 5.89 MHz, 8' mobile antenna and what happens to the standing wave current through the coil when 40' is added to the top of the antenna. The .EZ files are available for downloading from that web page. Anyone with a full-featured copy of EZNEC can duplicate my results. The *only* change between antennas is the addition of that 40' of wire. Everything else, including the frequency, stays the same. (The coil doesn't know that it is supposed to honor the lumped circuit model and reports the facts of physics.) The current "flowing" into the bottom of the coil is 1.29 amps. The current "flowing" out of the top of the coil is 2.07 amps. Seems that fact alone is enough to prove that standing wave current doesn't "flow" in the commonly accepted definition of the word. Guru gut feelings to the contrary, these results can easily be proven with real-world measurements by anyone to expend the time and effort. The r.r.a.a gurus have four days of peace in which to figure out a reasonable technical explanation for those EZNEC results. Enjoy! -- 73, Cecil http://www.qsl.net/w5dxp Article: 222625 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <122255j5m0eed84@corp.supernews.com> <1143019485.927955.293220@t31g2000cwb.googlegroups.com> Message-ID: Date: Wed, 22 Mar 2006 16:23:42 GMT Richard Clark wrote: > I, on the other hand (barring these misappropriated citations), have > busted this thread four times. In your mind, delusions of grandeur certainly seem to work. :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 222626 of rec.radio.amateur.antenna From: Allodoxaphobia Subject: Re: building a yagi Date: 22 Mar 2006 16:36:59 GMT Message-ID: References: On Wed, 22 Mar 2006 03:27:09 GMT, Leadfoot wrote: > I going to build a 11 element yagi but the problem I'm having is I can't > find the aluminum rods, I was wondering if I use copper if I will still get > the same Db gain. Ya, you'd get the same gain, but the antenna would be pretty damn heavy! Make your own AL rod like I do: Find AL wire -- about 8-10 gauge will do. It'll be soft and flexible -- not what you would chose for ant. elements. Well... Cut your elements out of the wire -- each about 5-6 inches _longer_ than you want. For each element, clamp one end in a bench vise and chuck the other end in a 3/8" or 1/2" electric drill. While pulling back on the drill, run the drill -- twisting the wire until you have 1 - 1 1/2 twists-per-inch in the element. (Much more than that will make it too brittle for use.) What you end up with is a nice, stiff, straight rod suitable for 2M antennas -- and higher in freq. I made a 6 el. vert 2M beam that I mounted on the fore-boom of my tri-bander http://jonz.net/W3DHJ/images/W3DHJ_Tower.jpeg from AL conductors that I scrounged from scrap ends of power cable from the local REA. There were six AL conductors wrapped around a steel core wire. The AL conductors were about 7/32" in dia. I got the 15' lengths (useless for them) for free. Now, if you have large roosting birds in your area, it might require heftier elements for a horizontal beam than I've described. i do not have such problems here. I'm pretty sure you could find large gauge AL ground wire in the electrical dept. at your local hardware emporium. HTH Jonesy -- Marvin L Jones | jonz | W3DHJ | linux 38.24N 104.55W | @ config.com | Jonesy | OS/2 *** Killfiling google posts: Article: 222627 of rec.radio.amateur.antenna From: "Frank" References: <1143039401.294306.151160@g10g2000cwb.googlegroups.com> Subject: Re: SMT Inductor(RF choke) with SRF about 3GHz Message-ID: Date: Wed, 22 Mar 2006 16:40:22 GMT www.coilcraft.com Regards, Frank "mazerom" wrote in message news:1143039401.294306.151160@g10g2000cwb.googlegroups.com... > where could i possibly buy high-valued inductors ( tens of uH) with an > SFR close to 3GHz.this will serve as my rf choke in conjuction of a > decoupling cap of 100nF...thanks > murata has good high frequency inductors but the problem is i cant find > one with high SFR.. > thanks! > Article: 222628 of rec.radio.amateur.antenna From: "Old Ed" References: Subject: Re: First Attempt Message-ID: Date: Wed, 22 Mar 2006 17:25:27 GMT Hi Michael, I tried Google search for salsawaves, and came up with a link to an OCF "Windom" antenna. But clicking on the link just led to a sort of highjack web page containing only ad links. 73, Ed "Michael Coslo" wrote in message news:dvrm88$1do0$1@f04n12.cac.psu.edu... > Old Ed wrote: > > Hi Michael, > > > > Thank you for your comments! I'd be interested in trading experiences > > with you on the OCF topic, either here or direct. Did you make one > > or buy one? > > I made mine. The design is a combination of one of the antennas on the > salsawaves site. (I don't have the URL handy, but if you google > salsawaves it will get you there.) The other section of the design was > with EZNEC demo. > > > > > I have interleaved some other responses below... > > > > 73, Ed > > > > "Michael Coslo" wrote in message > > news:dvmot3$1nle$1@f04n12.cac.psu.edu... > >> Old Ed wrote: > >>> Reg, > >>> > >>> The type of antenna you describe is very useful and popular. > >>> > >>> However, your assertion is much too sweeping as a generalization. > >>> In no particular order, here are some caveats: > >>> 1. The qualifier "best" is largely meaningless, absent an agreed > >>> set of weighted criteria for "goodness." (How important is: > >>> size? weight? cost? visual profile? bandwidth? instant QSY? > >>> gain? pattern? low-band performance vs. high-band performance? > >>> power-handling capacity? need for tuner? etc., etc., etc.) > >> I'm always hesitant to use words like "best" for all the reasons you > >> state, but I think that Reg qualified things pretty well. > > > > I think Reg's ONLY qualifiers were "all round, all band" (presumably > > meaning 80 thru 10). To me, that description falls well short of the > > mark, as "qualifiers." > > > >> Within the > >> qualifications of all band dipoles, the ladder-line fed general dipole > >> is pretty darn hard to beat. I recommend them to any new hams that ask > >> me for advice on antennas. > >> > > You can make a good case for this proposition. But I'm a bit puzzled > > on how these qualify as A-1 newbie antennas. > > > > First, our newbie to learn how to coddle finicky ladder line, bring it > > into the shack, and make the transition to unbalanced feed. Then he/she > > needs a crash course on transmatches: > > 1. Balanced or unbalanced design? (If unbalanced, may not work well > > with this antenna; if balanced, may not work with future, coax-fed > > antennas.) > > 2. Low or high power? (If low, may need to upgrade later.) > > 3. Manual or automatic? (If automatic, how interface to rig?) > > 4. Which brand and model? (Might Fine Junk or $quality$?) > > 5. New or used? > > 6. How do you operate the transmatch? > > I've always suggested cutting teeth on low power, then working your way > up. Mistakes are a lot less dangerous that way. In most cases, I suggest > the MFJ approach. I have one that is now in a emergency backup. My > thoughts on them are that they are certainly not the highest quality, > but they work, and you can always get rid of one to start another ham on > their way. > > > > If our newbie wants some power-handling capability, and plans > > to buy it new, he/she will need an extra 500 to 700 USD and more > > space on the desk. > > > > Re Reg's reference to a choke balun: I've been looking for good quality, > > commercial choke baluns equipped with SO-239 inputs and outputs. > > So far, I haven't found any; and I haven't been quite motivated enough > > to make one. What should our newbie do to get one, if needed? > > I've made all my baluns, 4:1 and choke, for my setup. But you raise a > good point, as I'll note below. > > >> My rationale is that most new hams these days buy rigs that are > >> all-band, transistorized units.These units are also sensitive to > >> mismatches between antenna and rig. Most new hams are not antenna gurus > >> either. So here is an antenna that will allow them to get on the air > >> without a lot of fussing. The only real measurement caveats are some > >> lengths that you don't want to use. > >> > > I can't quite see how slogging thru all the above is going to be easier for > > a newbie than buying a Buckmaster OCF or basic trap dipole, buying a > > ready-made coax jumper of the required length, and then doing plug- > > and-play with the (typical) rig's built-in auto-tuner. But it probably > > would be more educational. > > Ah, Ed, you have exposed me being shortsighted! I'm a compulsive > homebrewer, and I never considered buying a ready made antenna. The > other approach might be quite different than mine, and yet just as valid. > > > >> So we end up with an antenna that allows the newbie to get on the air, > >> allows them to learn some stuff by twiddling knobs and such, then when > >> they have a bit more experience, they can tackle that more "advanced > >> antenna" with it's more exacting design, trimming , and measurements. > >> > > I'm having a hard time figuring out what antenna type(s) would be "more > > advanced" than the random-length-doublet-with-outboard-ATU, and > > yet require more fiddling. > > If a person decides to make a trap or even more so a fan dipole, they > will be doing a lot of cutting and trimming and measuring. I've always > thought that for a newbie to get their feet wet, the less of that and > the more on-air experience with adjustments the better. > > > > But I will grant you this: IF someone decides from the get-go that they > > want a glitzy transmatch at their operating position--whether they need > > it or not--then the balanced-feeder doublet makes pretty good sense. > > This would be especially true if there wasn't enough space for something > > like a Buckmaster OCF, but there was enough space for (say) an 88' > > doublet. > > I've made an 88" doublet for field day. It was a very good antenna on > 20 and 40 meters, and so-so on 80.(still not too awful bad). I know > someone is going to ask me to define "Very good". In this case, I > received many unsolicited comments on good signal strength on 40 and 20, > had no trouble getting through on first call. On 80 I had to work a good > bit harder. > > It is good to get another perspective on this. > > > - 73 de Mike KB3EIA - - > > > >> > >>> 2. A good case can be made that choosing the "right" length is > >>> "better" than a random length, within this type. > >>> 3. An excellent case can be made that center-fed is NOT always > >>> the "best" option, within this type. > >>> 4. I'll let the fans of this antenna type chime in with why they > >>> prefer balanced tuners and/or tuned feeders to the use of an > >>> unbalanced tuner... if they want to. (I use more tailored > > antennas, > >>> and don't need a tuner of any kind, most of the time.) > >> As I do now. I've really been smitten with my OCF dipole, fed with > >> Coax, because in no small part, the feedpoint drops straight down to my > >> shack. That coupled with an automatic tuner in my radio , allowing me to > >> "plug and play. > >> > >> But I still strongly urge newcomers to put up one of those ladder line > >> dipoles for the experience. They work okay, too! 8^) > >> > >>> "Reg Edwards" wrote in message > >>> news:dvhp20$ap9$1@nwrdmz01.dmz.ncs.ea.ibs-infra.bt.com... > >>>> The best, all round, all band, antenna is a high centre-fed dipole of > >>>> no particular length, fed with an open-wire feedline of no particular > >>>> length or impedance, all the way to the shack, used with a choke-balun > >>>> and an unbalanced tuner. > >>>> > >>>> It is good down to the frequency at which the dipole is about > >>>> 1/3-wavelength long. > >>>> > >>>> Simplicity = efficiency. > >>>> > >>>> Once tried you will never return to anything else. > >>>> ---- > >>>> Reg. > >>>> > >>>> > >>> > > > > > > Article: 222629 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Current through coils Date: Wed, 22 Mar 2006 10:11:56 -0800 Message-ID: <12234rh79jg535e@corp.supernews.com> References: <121mh75g3ekkme9@corp.supernews.com> <121ojih732ucf6f@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> John Popelish wrote: > Cecil Moore wrote: >> We already know that, Ian. Please drag out your dusty math book >> and try to understand the difference between the standing wave >> current function, func(kx)*func(wt), and the traveling wave >> current function, func(kx +/- wt). They are obviously different. >> Calling the standing wave current a "current" is something of >> a misnomer since it doesn't exhibit the characteristics of a >> normal current at all. What are the implications of a "fixed >> phase" for a current, i.e. its phasor doesn't rotate? The total current ("standing wave current" in Cecil's parlance) certainly does have an associated phase angle, and its phasor certainly does rotate. (By "phase" I mean time phase.) A sinusoidal traveling current wave can be expressed as a phasor whose value is a function of position. When you add a forward traveling wave to a reverse traveling wave, you're adding two phasors. The result is a phasor whose value is the vector sum of those two phasors. This is the total current. It has magnitude and phase like any other phasor, and the same rotational speed as its components. A common manifestation of this is the standing wave pattern along a transmission line. In a transmission line with two current waves traveling in opposite directions, the phase of the total wave changes with position along the line. Only in the special case where the two waves are equal in amplitude (i.e., when the line is lossless and open or shorted at the end) does the phase of the total current -- the sum of the forward and reverse traveling waves -- turn out to be the same at all points along the line. This can be easily seen from the very well known equations describing wave behavior on transmission lines. There's no special "standing wave current" that's a "misnomer" or which is a phasor which "doesn't rotate". The total current is indeed a phasor -- its rotation speed is the rotational frequency, 2 * pi * f, just like the traveling wave components from which it can be made by simple addition. I think the problem Cecil is having with it is that the currents on an antenna behave in a manner that's similar to an open circuited transmission line, which results in the phase angle of the total current -- which can be represented as a phasor -- being the same at every point along the line. The total current isn't current which has "stopped flowing". Like the traveling wave currents it can be split into, it represents the movement -- specifically, the time rate of flow -- of charge. It can be represented by a phasor, which has magnitude and phase like any other. The phase is simply the same at all points along the line or wire. If the existence of the actual, total current presents problems for an analysis method, the problem lies with the analysis method, not that the total current has the imagined special properties Cecil is claiming. Once again, any system response such as the voltage across an inductor or the current at any point along an inductor or antenna can be calculated if desired by separately calculating its value resulting from a forward current wave and its value resulting from a reverse current wave. Then the two results can be added together to find the total response. If this sum does not exactly equal the response calculated directly from the total current, then the calculations are being done incorrectly. Roy Lewallen, W7EL Article: 222630 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Current through coils Date: Wed, 22 Mar 2006 10:16:07 -0800 Message-ID: <122353ci5sb807a@corp.supernews.com> References: <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <122255j5m0eed84@corp.supernews.com> <1143019485.927955.293220@t31g2000cwb.googlegroups.com> Richard Clark wrote: > On Wed, 22 Mar 2006 13:08:37 GMT, Cecil Moore > wrote: > >> False! Gene Fuller, Tom Donaly, and Roy Lewallen have all made >> postings that support my side of the argument against yours. There's very little about Cecil's theories that I agree with. He's made many statements which are completely false as I've pointed out numerous times, and his conclusions are largely based on misconceptions and faulty understanding of basic principles. Roy Lewallen, W7EL Article: 222631 of rec.radio.amateur.antenna From: Butch Magee Subject: Re: Wideband Folded Loop Construction Details Date: Wed, 22 Mar 2006 12:39:22 -0600 Message-ID: <12236f1jpu04sd2@corp.supernews.com> References: <1222o0f8rbouha3@corp.supernews.com> <1d88f3-52s.ln1@p400bob.personal.cox.net> Hello Bob and tnx for the reply. Check out http://www.rys.nl/wfl.html this one doesn't look like a dipole and a 7.5 by 1 meter space is all the space it takes up. There are no close up photos of the configuration, and can't tell where feed point is. I'm just full of no information today :o) I did a google search for wideband folded loop antenna, and was presented with this beauty of an antenna, but, like I said, no wiring details and it sells for 400.00!! You just must roll your own. Butch Bob Bob wrote: > Hi Butch > > Are you talking about the terminated folded dipole antenna? > > Mr Cebik has a rundown on them at; > > http://www.cebik.com/wire/wbfd.html > > and says that the antenna is "typically" 90ft long for 80-10m. There is > however a non trivial loss at 80m you may want to check on. > > If you like "no tuner" also consider Cecils w5dxp's doublet at; > > http://www.qsl.net/w5dxp/notuner.htm > > That uses sections of 450 ohm feedline that are swicthed in and out of > circuit. > > Cheers Bob W5/VK2YQA > > Butch Magee wrote: > >> >> >> Geltlemen, >> I have been considering the Wideband Folded Loop (WFL) Article: 222632 of rec.radio.amateur.antenna From: "RB" Subject: which is best? Message-ID: Date: Wed, 22 Mar 2006 12:55:14 -0600 Here's one for all our experts and gurus out there: Consider a 140' dipole up at 40' height. Used on 160-10m Other scenario is a 50' top loaded vertical, with 4 radials, 70' each, used on 160-20m. The question is which antenna gives us more radiated energy going out in useful directions? A fair amount of the dipole energy goes into the ground. Another big chunk goes into cloud warming. That leaves some energy going out at elevations which are useful to us. The vertical doesn't do much cloud warming. It does have some energy going to ground, but probably less than the dipole. However, it doesn't have nearly as much radiating surface as the dipole has. But, being top loaded, it does tend to get the current node maxed on the available vertical (radiating) surface. So, holding power input constant, etc, which antenna gives us the more useable rf energy output for hamming on 160-20m? Article: 222633 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <121ojih732ucf6f@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> Message-ID: Date: Wed, 22 Mar 2006 19:28:43 GMT John Popelish wrote: > Since, in both standing > waves and traveling waves, current at a point, changes magnitude and > sign in exactly the same way (at a point, they are indistinguishable), > they can both be described with phasor notation. Limiting oneself to a point measurement is handicapping onself. When the equation for standing wave current is compared to the equation for traveling wave current, the real differences are obvious. > For standing waves, the phasor of a neighboring point has the same phase > shift, ... Exactly! Therefore, it cannot be used to measure the phase shift through a coil or even through a wire. > But at any point along both standing waves and traveling waves, there > certainly is a phasor that represents the current at that point. For the standing wave current it is a phasor that doesn't rotate all up and down the wire. You have to admit, that's a weird phasor. It's more akin to DC than anything else. > You need to get past this misconception that standing waves are not > current and are not describable by phasors. Standing waves current is the superposition of two essentially equal currents traveling in opposite directions. If it was equal DC currents traveling in opposite directions, what would the net current be? -- 73, Cecil http://www.qsl.net/w5dxp Article: 222634 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <121mh75g3ekkme9@corp.supernews.com> <28826-441C4099-1651@storefull-3255.bay.webtv.net> <121ojih732ucf6f@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> Subject: Re: Current through coils Message-ID: <_5iUf.29$163.18@fe08.lga> Date: Wed, 22 Mar 2006 15:05:05 -0500 >> Ian White GM3SEK wrote: >> >> All the questions you ask other people are rooted in your own >> misconceptions. In other words, the questions are rigged so that they >> cannot be answered except by agreeing with you. > >Cecil, W5DXP wrote: > No, Ian, my questions are rigged so they cannot be answered except > by agreeing with the laws of physics and gurus cannot afford to show > their ignorance of the laws of physics. That leaves them between a > rock and a hard place as far as answering my questions are concerned. > That's the only reason for the "Silence of the Gurus". > -- Esteemed gentlemen: I am more of an engineer, inventor rather than scientist, analytic, cosine kind of guy. But I will elevate myself on an occasion to find the root of the problem and proof if needed. Let me try to put the things in perspective, from real life facts, to this "scientwific" debate about the "problem". 1. First I was smacked by the fact that on my 80m Hustler resonator, I re-shrinked, (burned) the insulation on the coil from the bottom up, while operating contest, mobile from Toronto, while spending few last days with my dear mother. I was running about 600W to regular (200W) 80m coil with heavier duty transmitting, during the contest, it was no surprise that it melted the heat shrink tubing covering the turns. Most people make occasional transmission and do not fry the coil even with more that what it is rated for. On 40m and up I rewound other coils with heavy wire or tubing and extended whips. I would not see the problem there. I appeared to me strange that the bottom of the coil was fried. Normally I would have expected either "uniform frying" , or perhaps more on the top due to the raising, accumulating heat. It kind of bothered me, because it was against the conventional "wisdom" or what I knew. 2. When the topic came up, Barry, W9UCW, knew about the effect and done some real life, real antennas, real RF ammeters measurements and found out that indeed, the RF current at both ends of a typical loading coil (quarter wave resonant, coil loaded vertical antenna) is different. He described it, offered some photos and data about the measurements. Please see http://www.k3bu.us/loadingcoils.htm In his example he showed that 40m typical, loaded vertical, had about 40% less current at the top than at the bottom. That made me happy, it made sense and explained what was happening with my Hustler. So I got some insight into the workings of the loaded, shortened radiator or element. Reality agreed with engineering measurements, experiment, that anyone can reproduce and verify. The conclusion was: "There IS a drop, difference in RF current across the antenna loading coil." The significance (to me anyway): Efficiency of the radiator, antenna is proportional to the area under the (cosine) curve of the current distribution across the radiator. The loading coil, as it turned out, had significant contribution to that current distribution that it got my attention. Knowing the effect, we can play with different position of the loading coil within the radiator and experiment with various ways of top loading, to maximize the current flow within the desired portion of the radiator, to maximize the area under the cosine current curve - to maximize the efficiency under given restriction for the particular antenna design. Here comes the compromise between loading inductance (coil, stub) vs. capacitive hat (T, L, disk) loading. So in the typical loaded (mobile or shortened) vertical we are trying to maximize the efficiency and it is important to know what is the current distribution across the radiator. If the coil has a drop in order of 40 - 60% as it appears to be, than that is significant to me to take it into the account. Knowing how to apply this effect will allow me to optimize, maximize the antenna performance. So far with me? If not, ask the questions or tell me where I am wrong. 3. Then Tom, W8JI and his followers, with some "backing" from literature (plenty are wrong), some experiments, modeling, came to "prove" that it can't be so. His conclusion: "The current in the antenna loading coil is the same at both ends". Then the "fight" and controversy started. It appears to me that JI camp is coming from the theoretical end of it, applying laws of physics and theories that do not apply to the case in question. 4. Cecil, W5DXP came to the rescue by explaining and modeling the case and supporting K3BU/W9UCW case and reality. We were happy to have that support, shining more light on the scientific side of the effect and effort to correlate the crude observations, real life measurements with theory, modeling and analytical end of it. 5. Not so fast. JI camp vehemently defended their "equal current" case, using examples, modeling, tailored to support their claims, for some reason ignoring the reality, measurements, experiments done to set the coil in the spot where current can be, and is the same (no argument with that). 6. Cecil, W5DXP started to dig deeper into the effect, showed that if we model the coil as a loading stub, EZNEC shows the difference in the current. When modeled as a solenoid, it also shows the difference. When the loading is inserted as a simple L (zero physical size) inductance, then EZNEC "proves" that current is the same. So for the same inductance, of different physical model (same electrical) properties EZNEC "proves" that each camp is "right". The only problem is, which case represents the reality and should be taken seriously. To prove the point further, Cecil showed that positioning the coil in various position within the radiator, one can aggravate the difference in current at the ends from one extreme of being equal, to the other extreme of being max at one end and zero at the other, depending on the size of inductor, position within the antenna and frequency applied. To me it makes sense, explains the "workings" of the effect, puts some numbers on it and shows how to model it, apply it and UNDERSTAND it. That's the way IT IS - the reality. Anyone can verify it, do the experiment (otherwise, please prove us wrong and where) and now - even model it in EZNEC when using proper definition of the model coil (solenoid or loading stub of equivalent inductance). 7. No, Cecil, didn't do the stupid mobile antenna trick with quarter wave extension. He used it as an example to show how one can play with the model to see the different situations and show that current can be from equal to extreme (max to zero) across the loading coil. In the EZNEC you can vary the position of the coil (solenoid or stub), length of the radiator and frequency to see the current value and distribution across the coil/radiator. Thanks to Cecil (and "solenoid" Roy), we have now improved way of modeling the effect, understanding it and better way of applying to antenna design. Thanks Cecil, you have golden patience, persistency and are a great defender of the TRUTH! 8. But Noooo! W8JI camp and non-believers can not accept that (reality). They cling to the "explanations" why it can't be so, because of "purple electrons, phasor eating extremists" would not allow it to be so. They are dancing around the facts and examples of why it is not so, not answering latest W5DXP questions, but the main thing - not verifying the reality with proper experiment or measurement (not important?). They are trying to prove that reality isn't, Tesla and others are fools, because of what??? Pride? Can't be wrong? Emperor has equal current clothes? 9. If anyone is trying to argue the case that (eventually) current is (or close to) equal, by arguing that sticking the coil at the base or where there is virtually no difference because of the position of the coil and current distribution in the radiator, forget it. We are not arguing that (and we agree with THAT special case). We are arguing with general statement, as displayed on W8JI pages and argued by the "guru followers" that the "RF current across the antenna loading coil IS (always) the same" (or close, losses, bla, bla) in the TYPICAL loaded or mobile antenna. NOT in the special case where it indeed can be. THAT WAS the subject of the discussion and problem that started all of this. Not current in ANY coil, in ANY circuit. We are not arguing minute diffrences due to radiation, resistance, capacitance surface effect, etc., we are arguing the difference of a 40 - 60 % of current drop across a typical loading coil in a typical mobile or loaded antenna. 10. According W8JI camp, looking at the quarter wave loaded whip, the current goes up the radiator according to cosine curve, then is the same across the coil, then tapers to zero at the tip in the triangular shape (should be the rest of the cosine curve, but close enough approximation). We are talking about typical loaded resonant quarter wave ant, (not any coil in any circuit). 11. According to K3BU camp, the same happens as above, except the current across the coil drops at the top of the coil to typical 60 - 40 % (for 80 - 40m) and then tapers to zero at the tip. Again, (I hope no dispute over this) efficiency of the antenna is proportional to the area under the current distribution curve across the radiator with the loading coil. So according to W8JI camp, the loaded radiator would have better efficiency than it really has, by about 60 - 40 % of the above the coil current curve area. 12. To me this is significant and worth exploring, because knowing the effect will allow me to better design, model and optimize antenna systems with loaded elements. The difference in the amount of current in the remaining portion of the antenna is not negligible and the effect will magnify itself when designing multielement loaded antennas. If the model shows wrong amounts and distribution of the current, the results will be off and real antenna will not perform as modeled. Those ARE the currents we consider in modeling, show their distribution off and calculate the antenna parameters with (right Roy?) So, to some the whole argument may be insignificant, to me it is, it should be known, properly considered and applied in the antenna modeling and design, otherwise it could cause inaccuracies and wrong results. 13. So where are we now? We have the effect, we have the measurements, we have explanation, we have the recipe how to model it properly, we have some results. Others can duplicate and verify it. (And answer the frickin Cecil's questions!!!!) Then we have W8JI camp that insists that it ain't so, twisting and dancing trying to "prove" that it just can't be so. Using "arguments" of their own, often contradicting themselves (ooops) that it just couldn't be, because, because, because.... Well, IT IS, if your egos like it or not. It is almost amusing to read the thread and arguments trying to defy the reality by "scinetwific proof". Cecil's arguments and question are selectively ignored and not argued, while new twists and detours are brought in. 14. So if the W8JI camp can not swallow reality, so be it, eventually live with giant egg on the face. I am extremely grateful to W9UCW, W5DXP and others in "our" camp for their contribution to the discussion, explanations, shedding their light and wisdom on the subject (and patience, and persistence). I have learned more about the loaded antennas and will use it especially in the design of receiving arrays for the new Tesla Radioclub salt water marsh 175 acre antenna farm (www.TeslaRadio.org) 15. One more time, friendly advise to Tom, W8JI: If you strongly defend posting the truth on Internet, live by it. It takes big guy to admit being wrong, learn and give credit where it is due! Ridiculing someone being wrong, especially when he is right is not in the spirit of ham radio and decency. Playing guru, engineer and pontificating might go well on TV show but in real life there are consequences. Arguing on a wrong side, then after realizing being wrong, going QRT for a while and then emerging as a guru and portraying the subject as own invention, without giving credit to "arguer" smells with plagiarism. I am saying this here, because I was few times publicly ridiculed by Tom while being right, as he later confirmed by eventually propagating "my gospel" as his own. We should be engaging in civil discussions and arguing about the topics, so we can all learn and be better. If this whole exercise will contribute to that, then it was worth it. If not, then keep on truckin'. 16. To the rest of the readers, I though that by now we all would be on the same "camp reality", but looks like there is still a rocky road ahead. I think we will get better results and go to radio heaven for sticking to the "current in loading coils" truth. I promised comprehensive article on the subject, but life keeps throwing more important problems in my path, but I will try hard to do it soon. We shall summarize our camp's wisdom and hope for convincing case for the unbelievers. I tried to portray the picture of reality and significance of the subject in hope of bringing the refusniks aboard. You all can be the judges of what good it was. We could look at some other "gospels" at Tom's web site, but that is another story when subject comes up. (All in the name of dispelling the myths and old waives tales as Tom likes to do.) I don't like to pick a fight, but I don't stand by when there is a significant myth or wrongo being propagated, I will defend the truth with my last breath (if it is worth it :-) I think 'nuf said, we all did our best to conway the reality, the readers can draw their own conclusions and if important, verify this and that to see who is RIGHT and if they can benefit from the findings. Good luck and I rest my "piece of coil". 73 Yuri Blanarovich, www.K3BU.us Article: 222635 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <12234rh79jg535e@corp.supernews.com> Message-ID: Date: Wed, 22 Mar 2006 20:06:37 GMT Roy Lewallen wrote: > The total current ("standing wave current" in Cecil's parlance) > certainly does have an associated phase angle, and its phasor certainly > does rotate. The standing wave current phasor in a 1/2WL thin-wire dipole *DOES NOT ROTATE* and is fixed *CONSTANT AT ZERO DEGREES*. Please reference Figure 14-2 in Kraus' "Antennas for All Applications", 3rd edition, page 464. It shows *ZERO* phase shift in the standing wave current >from tip to tip in the 1/2WL thin-wire antenna. It is obvious from the standing wave current equation that the phase angle doesn't change with position. This one misconception is what has got you and Tom totally confused. Please correct your misconception. It's the forward current phasor and reflected current phasor that does the rotating. Since they are rotating in opposite directions, the phasor sum of those two phasors is essentially *CONSTANTLY ZERO ACCORDING TO Kraus*. > (By "phase" I mean time phase.) A sinusoidal traveling > current wave can be expressed as a phasor whose value is a function of > position. When you add a forward traveling wave to a reverse traveling > wave, you're adding two phasors. The result is a phasor whose value is > the vector sum of those two phasors. This is the total current. It has > magnitude and phase like any other phasor, and the same rotational speed > as its components. A common manifestation of this is the standing wave > pattern along a transmission line. Roy, those two phasors that get added are *ROTATING IN OPPOSITE DIRECTIONS!* The phase of the sum of those two phasors is *CONSTANT*! If you had read: http://www.qsl.net/w5dxp/current.htm you would know that already. That's the mistake that you and Tom have been making for years and you are still making the same arrogant mistake. Don't you believe what Gene Fuller posted? ******************************************************************** >> Regarding the cos(kz)*cos(wt) term in a standing wave: > > Gene Fuller, W4SZ wrote: >> In a standing wave antenna problem, such as the one you describe, there is no >> remaining phase information. Any specific phase characteristics of the traveling >> waves died out when the startup transients died out. >> >> Phase is gone. Kaput. Vanished. Cannot be recovered. Never to be seen again. >> >> The only "phase" remaining is the cos (kz) term, which is really an amplitude >> description, not a phase. The so-called "phase reversal" in longer antennas is >> not really about phase either. It is merely a representation of the periodic >> sign reversal seen in a cosine function. ********************************************************************* > In a transmission line with two current waves traveling in opposite > directions, the phase of the total wave changes with position along the > line. No, it does NOT! at least not by more than a few degrees. In Func(kx)*Func(wt), the phase is divorced from position on the line. If you don't believe me, would you believe EZNEC? When I told Tom that I had measured unchanging phase all along a dipole, you said EZNEC shows the same thing. > Only in the special case where the two waves are equal in > amplitude (i.e., when the line is lossless and open or shorted at the > end) does the phase of the total current -- the sum of the forward and > reverse traveling waves -- turn out to be the same at all points along > the line. This can be easily seen from the very well known equations > describing wave behavior on transmission lines. That's true. Now take a look at Kraus' diagram referenced above. Kraus assumes the forward current and the reflected current on a 1/2WL thin- wire dipole are *EQUAL* in magnitude. The same assumption is approximately true for a 75m mobile antenna. > There's no special "standing wave current" that's a "misnomer" or which > is a phasor which "doesn't rotate". The total current is indeed a phasor > -- its rotation speed is the rotational frequency, 2 * pi * f, just like > the traveling wave components from which it can be made by simple addition. Sorry, Roy, you are just wrong on that one. Please dust off your old math book. Func(kx)*Func(wt) DOESN'T ROTATE with 'x'. For any 'x', it just stands there exchanging energy between the E-field and H-field. > I think the problem Cecil is having ... Methinks you had better do something about that beam in your own eye rather than worry about the speck in mine. >... with it is that the currents on an > antenna behave in a manner that's similar to an open circuited > transmission line, which results in the phase angle of the total current > -- which can be represented as a phasor -- being the same at every point > along the line. That's not a problem. That's exactly what Kraus and EZNEC both say. You are the one having a problem with it and you really need to correct your misconceptions before the discussion can progress. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222636 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <122255j5m0eed84@corp.supernews.com> <1143019485.927955.293220@t31g2000cwb.googlegroups.com> <122353ci5sb807a@corp.supernews.com> Message-ID: Date: Wed, 22 Mar 2006 20:08:38 GMT Roy Lewallen wrote: > There's very little about Cecil's theories that I agree with. But you did say EZNEC agreed with the phase measurements I reported for my dipole, i.e. so close to zero I couldn't tell any difference from zero. This leaves you in the unenviable position of disagreeing with (EZNEC and me). -- 73, Cecil http://www.qsl.net/w5dxp Article: 222637 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <12234rh79jg535e@corp.supernews.com> Message-ID: Date: Wed, 22 Mar 2006 20:11:01 GMT John Popelish wrote: > He is so close, but still has a couple misconceptions blocking him. If those are technical misconceptions, please let's discuss them. Last time, when I rewrote my posting to make the meaning clearer, you agreed with it. Perhaps, this is also another example of my poor writing style. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222638 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: which is best? References: Message-ID: Date: Wed, 22 Mar 2006 20:12:34 GMT RB wrote: > The question is which antenna gives us more radiated energy going out in > useful directions? Please define what "useful directions" personally means to you. I prefer NVIS for "useful directions". -- 73, Cecil http://www.qsl.net/w5dxp Article: 222639 of rec.radio.amateur.antenna From: "Martin Krawczyk" References: <98u2225s79cf2cth9dku65d7ni07e59jvf@4ax.com> Subject: Re: Balloon lifted wire antenna? Message-ID: Date: Wed, 22 Mar 2006 20:17:42 GMT "Richard Clark" wrote in message news:98u2225s79cf2cth9dku65d7ni07e59jvf@4ax.com... > On Wed, 22 Mar 2006 10:36:48 +0100, Deni > wrote: > > >looking for any tips advice etc. > > Hi Deni, > > Make sure you are not violating any civil airspace rules. One > consideration is how do you insure your balloon will not escape? > Another consideration is to make sure the balloon is some distance > away from the end of the wire. Tying the wire to the balloon invites > the high potential at the end of that wire to explode *POP* the > balloon. > > 73's > Richard Clark, KB7QHC also take into acount weather conditions. i have had experience of a much larger balloon which acted like a lightning magnet. Article: 222640 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: Subject: Re: which is best? Message-ID: Date: Wed, 22 Mar 2006 15:27:13 -0500 If you can answer which is best: Mac truck or Corvette? We can answer your question. It depends on lot of things, what you want to do with it (who to communicate with, where, when, what band) etc. You need to consider propagation modes and nuances Know the antenna patterns for particular band Antennas are a fascinating subject and there is a lot of information in the literature and worth studying if one is serious about operating on the bands. Knowing that, one could do good job in selecting or designing the antennas for particular task. Yuri, K3BU.us Article: 222641 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <85ydnUdYMN0xMbzZnZ2dnUVZ_vednZ2d@adelphia.com> Message-ID: Date: Wed, 22 Mar 2006 20:36:00 GMT John Popelish wrote: > Cecil Moore wrote: >> Exactly! Therefore, [standing wave phase] cannot be used to measure the phase shift >> through a coil or even through a wire. > > I agree, unless you use phase measurement to hunt for the location of > the current nodes that have moved as a result of adding the coil. > Finding a phase reversal at opposite ends of the coil, for instance, > implies that an odd number of nodes reside in the coil. John, I didn't say the amplitude couldn't be used to determine phase. The current nodes are associated wiht amplitudes, not phase. > A phasor rotates at the reference frequency, and with a phase angle that > represents the angular difference between the value in question and the > reference cycle. Pick a point on the conductor, and if it carries > either a standing or traveling wave (or any combination of traveling > waves at the reference frequency), the current at that point is > describable as a phasor (having a specific magnitude, and a specific > phase with respect to the reference cycle). Yes, but the standing wave phasor doesn't change phase with position. The traveling wave phasors change phase with position. That's a big difference. > No. Currents do not travel. Current is the movement of charge past a > point. So current doesn't flow and all the references to "current flow" are wrong? If so, your task is a lot bigger than mine. May I suggest a new thread titled, "Current Doesn't Flow". -- 73, Cecil http://www.qsl.net/w5dxp Article: 222642 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Current through coils Date: Wed, 22 Mar 2006 12:47:52 -0800 Message-ID: <1223dvop83mkq9a@corp.supernews.com> References: <121mh75g3ekkme9@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <85ydnUdYMN0xMbzZnZ2dnUVZ_vednZ2d@adelphia.com> John Popelish wrote: > . . . > I think I agree with just about every conclusion you are making about > treating coils as slow wave transmission lines. . . A coil itself isn't a slow wave transmission line. In conjunction with shunt C, it can be analyzed as a transmission line, but only in conjunction with shunt C. Remove the shunt C and it ceases looking like a transmission line. The earlier example of the modification to Cecil's EZNEC model illustrated this -- when the ground (the other side of the shunt capacitor) was removed, the current drop across the coil disappeared. As far as considering a coil itself as a "slow wave structure", Ramo and Whinnery treat this subject. It's in the chapter on waveguides, and they explain how a helix can operate as a slow wave waveguide structure. To operate in this fashion requires that TM and TE modes be supported inside the structure which in turn requires a coil diameter which is a large part of a wavelength. Axial mode helix antennas, for example, operate in this mode. Coils of the dimensions of loading coils in mobile antennas are orders of magnitude too small to support the TM and TE modes required for slow wave propagation. Roy Lewallen, W7EL Article: 222643 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <12234rh79jg535e@corp.supernews.com> Message-ID: Date: Wed, 22 Mar 2006 20:47:50 GMT John Popelish wrote: > It may be you or I may have an untied shoe. In any case, Jim, oops, I mean John, here's the IEEE Dictionary's definition of current. "current - The flow of electrons within a wire or a circuit: measured in ampheres." And no, there is no definition for "current flow" in the IEEE Dictionary. "Current flow" and "power flow" are commonly used terms to signify "charge movement" and "energy movement". Objecting to the use of the words "current flow" is really picking at infinitessimal nits. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222644 of rec.radio.amateur.antenna From: "Steve Nosko" Subject: Re: Quad Antenna Date: Wed, 22 Mar 2006 14:19:31 -0600 Message-ID: References: Howard, If you mean the polarization (horizontal vs. vertical), yes. 73, Steve, K9DCI "Howard W3CQH" wrote in message news:zPGdnR_G5aU_Cr3ZRVn-gA@adelphia.com... > Question - Is the polarity of the antenna based on the feed point? > > 73's > > Article: 222645 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <85ydnUdYMN0xMbzZnZ2dnUVZ_vednZ2d@adelphia.com> <1223dvop83mkq9a@corp.supernews.com> Message-ID: Date: Wed, 22 Mar 2006 21:12:43 GMT Roy Lewallen wrote: > A coil itself isn't a slow wave transmission line. In conjunction with > shunt C, it can be analyzed as a transmission line, but only in > conjunction with shunt C. A 75m bugcatcher has its own shunt C called "distributed capacitance". It's what causes the self-resonant frequency of my 75m bugcatcher coil to be only 60% higher than the 4 MHz operating frequency. > Remove the shunt C and it ceases looking like a transmission line. That's true *only* for a lumped-circuit inductance. It is NOT true for a 75m bugcatcher which has it very own distributed capacitance built in. It is *IMPOSSIBLE* to remove the distributed shunt capacitance from a 75m bugcatcher coil. > The earlier example of the modification to Cecil's > EZNEC model illustrated this -- when the ground (the other side of the > shunt capacitor) was removed, the current drop across the coil disappeared. That may be true but please tell us how to remove the ground from a 75m mobile bugcatcher mobile antenna installation. > Coils of the dimensions of loading coils in mobile > antennas are orders of magnitude too small to support the TM and TE > modes required for slow wave propagation. Sorry Roy, Dr. Corum disagrees with your statement. You really should read the details of the Dr. Corum web page references that I posted. His test for the validity of his helix equations is: 5*N*D^2/lamda(0) <= 1 where N is number of turns, D is diameter, and lamda(0) is the self-resonant frequency. That value for my 75m bugcatcher coil is 0.4 so his equation for velocity factor is valid. The velocity factor for my 75m bugcatcher coil calculates out to be 0.0175. Now that's what I call a "slow wave" coil. But I have offered all these references weeks ago. Are you too arrogant to even have read them? (Another rhetorical question) -- 73, Cecil http://www.qsl.net/w5dxp Article: 222646 of rec.radio.amateur.antenna From: "RB" References: Subject: Re: which is best? Message-ID: Date: Wed, 22 Mar 2006 15:17:27 -0600 If we get rid of cloud warming angles of elevation, I guess we're left with NVIS. I think that's what I would call a useful direction. Article: 222647 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: which is best? References: Message-ID: Date: Wed, 22 Mar 2006 21:50:05 GMT RB wrote: > If we get rid of cloud warming angles of elevation, I guess we're left with > NVIS. I think that's what I would call a useful direction. NVIS *IS* cloud warming angles of elevation. Those are the ones I prefer for my type of operation. Who wants to talk to strangers who don't speak Texan? :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 222648 of rec.radio.amateur.antenna From: "Troy Majors" Subject: Multiband Dipole Angles Message-ID: Date: Wed, 22 Mar 2006 22:17:19 GMT What effect will the following have: both legs of the multiband dipole 60 to 65 feet up in the air cannot be in a straight line, but one leg must vary from a true north-south diple to the northeast at about a 35-40 degree angle from the other leg. Also, both legs slant downward in a slight inverted-V configuration, probably about 20-25 degrees. The feed line will come straight down at a 90 degree angle from the dipole legs, but will then split the difference in its horizontal move along the ground to the house. How much do I lose from all this compared to a dipole with both legs straight in line, and the feedline 90 degrees from the dipole both vertically and horizontally? All this is driven by the size of the lot, the placement of the trees in the back and front yards, the direction and density of the various limbs off the trees, and the level of my skill with a slingshot. I have the pilot ropes in place but have not raised the antenna yet. Any advice before I commit to this configuration? Thanks, Troy Article: 222649 of rec.radio.amateur.antenna From: "hasan schiers" Subject: Radials Date: Wed, 22 Mar 2006 16:42:47 -0600 Message-ID: I'm having trouble resolving the values produced by Reg's "Radials2" program and the excellent section in ON4UN's Low Band DX'ing, 4th Edition. Reg's work seems to be saying that placing radials on the ground shorten their resonant point such that having radials the recommended 1/4 wave physical length is not necessary, or even desirable. When I played with the program, the losses reported by Reg's program with radials as short as 10 or 20 feet were quite low, with sufficient number of them. Is this overly optimistic? (1/4 wave vertical) Here are the points of departure that I'm having trouble "resolving". Quoting from Chapter 9, section 10, Part 2.1.2: "A 1/4 wave wire that is resonant above ground, is no longer resonant on or near the ground. Typically for a wire on the ground, the physical length for 1/4 wave resonance will be approximately 0.14 wavelength." (the exact length depending on ground quality)" This seems to agree at least somewhat, with Reg's assumptions in his program. However, when we get to section 2.2.3 (again in Chapter 9, section 10), John asserts: "As soon as you use a larger number of equally spread radials, the RESONANCE EFFECT DISAPPEARS, and the radials form a disk, which becomes a screen with NO resonance characteristics. In this case, we no longer talk about length of radials, but about the diameter of a disk hiding the lossy ground from antennas." Unless I misunderstood Reg's program, it seems to maintain the idea of velocity factor/resonance in radials, no matter how many there are. John Devoldre (ON4UN), then goes on to describe the early work by Brown, Lewis and Epstein, as well as the exquisite study done by N7CL where he developed a formula for optimizing radial systems based on amount of available wire. The magic number for efficiency in a radial field appears to be 0.015 wavelength tip to tip spacing at the radial perimeter. Fewer wires and larger spacing degrade the radial field performance. More wires and closer spacing do not improve performance significantly. The formula looks like this: N = ((2*PI*L)^0.5)/A Where N = the number of radials, L = the amount of available wire and A = the tip to tip distance (1.3 meters for the 80m band) For 500 meters of available wire, the most efficient use of the wire is: N = ((2*PI*500)^.5)/1.3 or 43 radials. The length of the radials is 500 meters/43 or 11.6 meters long. This arrangement maintains the .015 wavelength tip to tip separation at the perimeter. ===================================================== Now, the case for perfection: Section 2.1.3.2 "From these almost 70 year old studies (BLE), we can conclude that 60 1/4 wave long radials is a cost-effective OPTIMAL, solution for amateur purposes. The following rule was EXPERIMENTALLY derived by N7CL and seems to be very sound and easy one to follow." "Put radials down in such a way that the distance between their tips is not more than 0.015 wavelength. This is 1.3 meters for 80 meters and 2.5 meters for 160 meters." The circumference of a circle with a radius of 1/4 wavelength is 2*PI*0.25 = 1.57 wavelength. At a spacing of 0.015 wavelength at the tips, this circumference can accommodate 1.57/0.015 = 104 radials. With this configuration you are within 0.1 dB of maximum gain over average to good ground. If you space the tips 0.03 wavelength, you will lose about 0.5 dB." "In general, the number that N7CL came by experimentally, closely follow those from Brown, Lewis and Epstein." ===================================================================== Now, Reg has in the past, objected to the BLE data because they didn't measure ground conditions. This issue is dealt with by N7CL, but it is too rigorous for me to type into this message. Suffice it to say, the formula appears to hold NO MATTER WHAT the ground conditions are like....i.e., the best use of an available length of radial wire (several hundred meters), is the formula listed above, and there is no resonance effect, no velocity factor effect (that is meaningful)... This seems to challenge, at its core, Reg's assumptions for his program on radials. Or am I missing something? There is no doubt that there is some agreement with Reg, but there are several points of departure, that strangely enough lead us back to B,L and E as being the most authoritative and experimentally verified data. That is not to say the B,L & E data is very well explained....but...with the addition of N7CL's work, radials are now "manageable for the masses", and the two studies appear to agree. Anyway, I found this stuff a lot more interesting than the endless bickering about magical properties of phasors, lumped constant vs. distributed networks, and when is an inductor an inductance, ad nauseum, so I thought I throw this out and see if anyone else finds it interesting and would like to comment. 73, ...hasan, N0AN Article: 222650 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: Wideband Folded Loop Construction Details References: <1222o0f8rbouha3@corp.supernews.com> <1d88f3-52s.ln1@p400bob.personal.cox.net> <12236f1jpu04sd2@corp.supernews.com> Message-ID: <9uu8f3-uks.ln1@p400bob.personal.cox.net> Date: Wed, 22 Mar 2006 16:16:08 -0600 Hi Butch Okay it looks like a T2FD that has been folded over. Usually they have a load resistor (600 ohms maybe) and a toroid matching transformer at the feedpoint. (The antenna is close to 600 ohms without the transformer) Cebik explains how much loss this system incurs so you can make some judgements from that. The smaller capture area than a "real" T2FD may mean another 3-6dB or so of loss. You might like also to look at a magloop generally. ie a loop antenna with a tuning cap at one location. I have seen these described as working well over a 2:1 freq range (eg 80 and 40m) and a few quoting 3:1. You usually need to remote tune them though with something like a srewdriver motor. As mentioned in the advert one of their claims to fame is lower received noise and with the tuning less off frequency interference issues. Whats your application, what bands do you want to cover and what space do you have? Bob Butch Magee wrote: > > > Hello Bob and tnx for the reply. Check out http://www.rys.nl/wfl.html > this one doesn't look like a dipole and a 7.5 by 1 meter space is all > the space it takes up. There are no close up photos of the > configuration, and can't tell where feed point is. I'm just full of no > information today :o) I did a google search for wideband folded loop > antenna, and was presented with this beauty of an antenna, but, like I > said, no wiring details and it sells for 400.00!! You just must roll > your own. > > Butch > Article: 222651 of rec.radio.amateur.antenna From: "RB" References: Subject: Re: which is best? Message-ID: Date: Wed, 22 Mar 2006 17:06:42 -0600 Well, I'm still getting tripped up in my terms. Not doing too well, here. What I'm looking for is max low angle radiation comparison of the two. Article: 222652 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils - BFD References: Message-ID: <%mlUf.41129$_S7.34746@newssvr14.news.prodigy.com> Date: Wed, 22 Mar 2006 23:48:11 GMT Richard Clark wrote: > "The current in a typical loading coil in the shortened antennas > drops across the coil roughly corresponding to the segment of the > radiator it replaces. " > 4. a 1:1 relation between loading coil and > "the segment of the radiator it replaces." Sorry Richard, Since you deliberately distorted what Yuri said, everything else you say is irrelevant. What is it about "roughly" that you don't understand? "Roughly" could mean +/- 50% accuracy. Why do you guys feel you have to distort everything in order to win a technical argument? If you are so technically correct, just give us the technical facts and skip the deliberate distortions. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222653 of rec.radio.amateur.antenna From: Jim - NN7K Subject: Re: SWR Tells Me?? References: <0df222l7igln084ed4hs1ohte1u5sukspr@4ax.com> Message-ID: Date: Thu, 23 Mar 2006 00:59:20 GMT Must comment- that the answer is "MAYBE"! It depends on what is UNDER that roof! If you have metal flashing (near vents, furnace pipeing), or insulation with a "VAPOR BARRIER" usually, aluminium foil backed, it may affect your ability to xmit a signal , and in the case of the latter, might make a great "FARIDAY SHIELD" (signal proof room)! And this would apply to comercial antennas as well! Tho, the wood in a roof, and the roofing material should be generally passive to even UHF, the other materials might be a problem. Dont give up hope, as have friend witha antenna (quad), on 6 meters, and 2 meters, in an attic dormer, if it had been insulated correctly, would have been relatively RF Proof! Might want to examine it before betting too complex! Jim -NN7K >>> >>>>"jimbo" wrote in message >>>>news:RZadnXHuHeVRmb3Z4p2dnA@comcast.com... >>>> >>>> >>>>>jimbo wrote: >>>>> >>>>> >>>>>Thanks for all of the advice. I have one more question. Can I tune a >>>>>J-Pole antenna in my shop and then move it to the attic and expect the >>>>>same performance? In other words, is an antenna an antenna or is an >>>>>antenna and it's installation an antenna? >>>>> >>>>>It would seem to me that if the antenna is tuned and works in my shop >>>>>it should work in the attic. Otherwise, how do "store bought" antennas >>>>>work? >>>>> >>>>>Thanks, jimbo >>>> Article: 222654 of rec.radio.amateur.antenna From: "Dan, danl, danny boy, Redbeard, actually Greybeard now" Subject: Re: Balloon lifted wire antenna? Message-ID: <2ru322p4obp7gfbb47sdap3vhh4hm0fhru@4ax.com> References: <98u2225s79cf2cth9dku65d7ni07e59jvf@4ax.com> Date: Wed, 22 Mar 2006 19:41:28 -0600 On Wed, 22 Mar 2006 08:22:27 -0800, Richard Clark sent into the ether: >>>On Wed, 22 Mar 2006 10:36:48 +0100, Deni >>>wrote: >>> >>>>looking for any tips advice etc. >>> >>>Hi Deni, >>> >>>Make sure you are not violating any civil airspace rules. One >>>consideration is how do you insure your balloon will not escape? >>>Another consideration is to make sure the balloon is some distance >>>away from the end of the wire. Tying the wire to the balloon invites >>>the high potential at the end of that wire to explode *POP* the >>>balloon. >>> >>>73's >>>Richard Clark, KB7QHC Power Pro fishing line comes to mind as a good tether. 50# is very thin(same as 12# mono), light(150yrds maybe 2/4 ounces with the spool?) and amazingly strong. Put it on an old fishing reel and it's ready to reuse any time you want. I've learned that I don't suffer from insanity, I enjoy it! (That is what my X-wife told me) danl4x@charter.net Remove the x for e-mail reply www.outdoorfrontiers.com www.SecretWeaponLures.com A proud charter member of "PETAF", People for Eating Tasty Animals and Fish!!! Article: 222655 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <85ydnUdYMN0xMbzZnZ2dnUVZ_vednZ2d@adelphia.com> Message-ID: Date: Thu, 23 Mar 2006 02:26:59 GMT John Popelish wrote: > If you can measure phase, you can see that it is opposite on opposite > sides of a node. There is a 180 degree phase shift each time the > measurement passes over a node. Do you disagree? Yes, but you can tell that from the amplitude being zero. > That's exactly the difference. But if you measure a single point, you > can't tell whether you are measuring a point on a traveling wave or a > standing wave. Agree? I agree but who would be stupid enough to measure just a single point? One could wear a blindfold and use no hands and have an even greater challenge. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222656 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <12234rh79jg535e@corp.supernews.com> <1143077128.011283.306270@v46g2000cwv.googlegroups.com> Message-ID: Date: Thu, 23 Mar 2006 02:42:49 GMT K7ITM wrote: > (Yawn) So, I have this system where there's a wave in each direction > and they are identical amplitudes so that there is zero loss to > radiation or thermal dissipation. And in this system there is a series > coil through which the waves pass, and the current at each end of the > coil is different amplitude. That means that the coulombs/second > passing a point at one end of the coil is different than the > coulombs/second passing the other end of the coil. Sorry, you are wrong about that. Here's why. For simplicity, let's assume the coil is lossless, 45 degrees long, and the forward and reflected current magnitudes are both equal to one amp. These assumptions are for purposes of illustration only. One amp of forward current is flowing into the coil and one amp of forward current is flowing out of the coil. Charge is balanced. One amp of reflected current is flowing into the coil and one amp of reflected current is flowing out of the coil. Charge is balanced. Note there is ZERO charge imbalance in the coil. The forward and reflected currents are all there are and they are balanced. The forward current at the bottom of the coil is 1 amp at zero degrees. The reflected current at the bottom of the coil is 1 amp at zero degrees. Adding them together yields a standing wave current of 2 amps at zero degrees. Do you know how to do phasor math? The forward current at the top of the coil is 1 amp at -45 degrees. The reflected current at the top of the coil is 1 amp at +45 degrees. Adding them together yields a standing wave current of 1.414 amps at zero degrees. Do you know how to do phasor math? The standing wave current at the bottom of the coil is 2 amps. The standing wave current at the top of the coil is 1.414 amps. THERE IS *NO CURRENT IMBALANCE* BECAUSE THAT STANDING WAVE CURRENT IS NOT REALLY FLOWING. IT IS JUST STANDING THERE. That's the entire point. > What happens to that imbalance in charge? Imbalance in charge is a myth, an old wives' tale. There is NO imbalance in charge. SEE ABOVE! -- 73, Cecil http://www.qsl.net/w5dxp Article: 222657 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <_5iUf.29$163.18@fe08.lga> <1143077338.694612.238920@z34g2000cwc.googlegroups.com> Message-ID: <_3oUf.58565$H71.18677@newssvr13.news.prodigy.com> Date: Thu, 23 Mar 2006 02:52:42 GMT w8ji@akorn.net wrote: > The point I (and others) tried to make was that in a small inductor > current was essentially equal at both ends of the coil, ... A 75m bugcatcher coil is NOT a small inductor. It is a slow- wave structure with a velocity factor of about 0.017, both measured and calculated. That gives my bugcatcher coil an electrical length at 4 MHz of about ~60 degrees. > This is because the inductor does not replace a certain "electrical > degrees" and have a cosine current drop related to those degrees. Sorry, Tom, Dr. Corum has proven you wrong on that score. A 1/2WL thin-wire dipole has a perfect cosine curve. Other structures deviate away from that perfect cosine curve. The coil certainly deviates away from that perfect cosine curve. But if you look at the current waveforms at: http://www.k6mhe.com/n7ws/Loaded%20antennas.htm figure 3, you can still see the outline of that cosine curve. > I can take an antenna of specific height and vary current taper in the > inductor quite a bit just by changing the style of loading coil. You can take the same loading coil and move it around in a standing wave environment and obtain any current distribution including current flowing into both ends of the coil at once. > It is the idea that the loading coil drops a certain current because of > "electrical degrees" that is so untrue. Sorry, Tom, that's just an old wives' tale of yours. Please respond to my new thread, "Silence of the Gurus". -- 73, Cecil http://www.qsl.net/w5dxp Article: 222658 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <12234rh79jg535e@corp.supernews.com> <1143077128.011283.306270@v46g2000cwv.googlegroups.com> Message-ID: Date: Thu, 23 Mar 2006 02:58:15 GMT John Popelish wrote: > K7ITM wrote: >> What happens to that imbalance in charge? Where does it go? What do >> we call something that behaves that way? What's so freakin' special >> about that? > > The charge briefly piling up and then being sucked out of such an > inductor is the same place charge piles up and is sucked out of parts of > a transmission lines with standing waves on them. Seems you got sucked in by a myth, John. The forward current is equal at both ends of the coil. The reflected current is equal at both ends of the coil. That takes care of any question of charge imbalance. There simply isn't any. Assume the coil is 90 degrees long and that the forward current is one amp and the reflected current is one amp. At one end of the coil, the forward and reflected currents are 180 degrees out of phase. The standing wave current is zero. At the other end of the coil, the forward and reflected currents are in phase. The standing wave current is 2 amps. Now do you see why standing wave current is considered not to be flowing? -- 73, Cecil http://www.qsl.net/w5dxp Article: 222659 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Current through coils Date: Wed, 22 Mar 2006 19:19:08 -0800 Message-ID: <12244tdjaher025@corp.supernews.com> References: <121mh75g3ekkme9@corp.supernews.com> <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <85ydnUdYMN0xMbzZnZ2dnUVZ_vednZ2d@adelphia.com> <1223dvop83mkq9a@corp.supernews.com> John Popelish wrote: > Roy Lewallen wrote: >> John Popelish wrote: >> >>> . . . >>> I think I agree with just about every conclusion you are making about >>> treating coils as slow wave transmission lines. . . >> >> >> A coil itself isn't a slow wave transmission line. > > Not at all? It seems to me that any real, physical inductor must have > some lumped properties and some transmission line properties, and it is > the balance of these that must be considered in any particular case to > decide which analysis is the more accurate way to deal with it in a > circuit. Solenoidal air core inductors have a lot of transmission line > properties if the frequency is high enough. If this were not so, they > would look exactly like fixed capacitors above self resonance, instead > of having multiple impedance peaks and valleys. > >> In conjunction with shunt C, it can be analyzed as a transmission >> line, but only in conjunction with shunt C. > > But any real, physical inductor has shunt capacitance to its > surroundings. So if you neglect this without considering whether or not > this is reasonable, you are going to be blindsided by its effects, > eventually. I don't disagree with anything you've said. The point I was trying to make was that the resemblance of a coil to a transmission line depends not only on the coil but also its capacitance to other objects -- and not to its relationship to traveling current waves. One thing I've seen done on this thread is to use the C across the inductor in transmission line formulas, appearing to give the coil a transmission line property all by itself and without any external C. This is incorrect. > >> Remove the shunt C and it ceases looking like a transmission line. > > How do I remove the shunt C of an inductor? With an active guarding > scheme? Actually, you can reduce it to a negligible value by a number of means. One I've done is to wind it as a physically small toroid. In the example discussed in the next paragraph, removing ground from the model reduces the external C to a small enough value that the current at the coil ends become nearly equal. That of course isn't an option in a real mobile coil environment, but it illustrates that the current drop from one end to the other, which in some ways mimics a transmission line, is due to external C rather than reaction with traveling waves as Cecil claims. In my modification to Cecil's EZNEC file I showed how the coil behaves the same with no antenna at all, just a lumped load impedance. As long as the load impedance and external C stay the same, the coil behavior stays the same. This isn't, however, to discount the possibility of the coil interacting with the antenna's field. It just wasn't significant in that case. >> The earlier example of the modification to Cecil's EZNEC model >> illustrated this -- when the ground (the other side of the shunt >> capacitor) was removed, the current drop across the coil disappeared. > > So whether or not this coil is acting as a slow wave transmission line > in addition to being inductive depends on the surrounding fields and > connections? I have no trouble with that. Well, not a "slow wave" transmission line. We shouldn't confuse an ordinary lumped LC transmission line approximation with a true slow wave structure such as a helical waveguide (next item). The propagation velocity of the equivalent transmission line is omega/sqrt(LC), so the speed depends equally on the series L and the shunt C. And let's talk for a minute about the coil "acting like" a transmission line. A transmission line is of course a distributed circuit. But you can make a single pi or tee section with lumped series L and shunt C which has all the characteristics of a transmission line at one frequency(*), including time delay, phase shift, characteristic impedance, impedance transformation, and everything else. If put into a black box, you wouldn't be able to tell the difference among the pi, tee, or transmission line -- at one frequency. You could even sample the voltage and current with a Bird wattmeter and conclude that there are traveling voltage and current waves in both cases, and calculate the values of the standing waves on either "transmission line". And this is with a pure inductance and capacitance, smaller than the tiniest components you can really make. With a single section, you can mimic any transmission line Z0 and any length from 0 to a half wavelength. (The limiting cases, however, require some components to be zero or infinite.) So you can say if you wish that the inductor in this network "acts like" a transmission line -- or you can equally correctly say that the capacitor does, because it's actually the combination which mimics a transmission line. But only over a narrow range of frequencies, beyond which it begins deviating more and more from true transmission line behavior. To mimic longer lines or mimic lines over a wider frequency range requires more sections. So what can we conclude about inductors from this similar behavior? Certainly not that there's anything special about inductors interacting with traveling waves or that inductors comprise some kind of "slow wave structure". The duality comes simply from the fundamental equations which describe the nature of transmission lines, inductances, and capacitances. Because the LC section's properties are identical to a transmission line's at one frequency, we have our choice in analyzing the circuit. We can pretend it's a transmission line, or we can view it as a lumped LC network. If we go back to the fundamental equations of each circuit element, we'll find that the equations end up exactly the same in either case. And the results from analyzing using each method are identical -- if not, we've made an error. The coil in the EZNEC model on Cecil's web page acts just like we'd expect an inductor to act. With ground present constituting a C, the circuit acts like an L network made of lumped L and C which behaves similarly to a transmission line. With ground, hence external C, absent, it acts like a lumped L. (There are actually some minor differences, due to imperfect coupling between turns and to coupling to the finite sized external circuit.) The combination of L and C "act like" a transmission line, just like any lumped L and C. And it doesn't care whether the load is a whip or just lumped components. (*) It actually acts like a transmission line at many frequencies, but a different length and Z0 of line at each frequency. To mimic a single line over a wide frequency range requires additional sections. >> As far as considering a coil itself as a "slow wave structure", Ramo >> and Whinnery treat this subject. It's in the chapter on waveguides, >> and they explain how a helix can operate as a slow wave waveguide >> structure. To operate in this fashion requires that TM and TE modes be >> supported inside the structure which in turn requires a coil diameter >> which is a large part of a wavelength. Axial mode helix antennas, for >> example, operate in this mode. Coils of the dimensions of loading >> coils in mobile antennas are orders of magnitude too small to support >> the TM and TE modes required for slow wave propagation. > > I'll have to take your word for this limitation. But it seems to me > that the length of the coil in relation to the wavelength and even the > length of the conductor the coils is made of are important, also. Important for what? No matter how long the coil or how many turns of the wire, a small (in terms of wavelength) inductor won't act like a slow wave structure or an axial mode helical antenna. This is for the same reason that a two inch diameter pipe won't perform as a waveguide at 80 meters -- there's not enough room inside to fit the field distribution required for that mode of signal propagation. There will of course be some point at which it'll no longer act as a lumped inductor but would have to be modeled as a transmission line. But this is when it becomes a significant fraction of a wavelength long. If the turns are very loosely coupled to each other, the wire length becomes more of a determining factor. As I mentioned in earlier postings, there's a continuum between a straight wire and that same wire wound into an inductor. As the straight wire is wound more and more tightly, the behavior transitions >from that of a wire to that of an inductance. There's no abrupt point where a sudden change occurs. Roy Lewallen, W7EL Article: 222660 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <85ydnUdYMN0xMbzZnZ2dnUVZ_vednZ2d@adelphia.com> <1223dvop83mkq9a@corp.supernews.com> <12244tdjaher025@corp.supernews.com> Message-ID: Date: Thu, 23 Mar 2006 03:26:16 GMT Roy Lewallen wrote: > Well, not a "slow wave" transmission line. We shouldn't confuse an > ordinary lumped LC transmission line approximation with a true slow wave > structure such as a helical waveguide (next item). The propagation > velocity of the equivalent transmission line is omega/sqrt(LC), so the > speed depends equally on the series L and the shunt C. Dr. Corum gives a formula for calculating the velocity factor of coils which meet a certain criteria. My 75m bugcatcher coil meets that criteria. It's velocity factor calculates out to be 0.0175. It's measured velocity factor is 0.015. That sounds like a "slow wave" device to me. > The coil in the EZNEC model on Cecil's web page acts just like we'd > expect an inductor to act. With ground present constituting a C, the > circuit acts like an L network made of lumped L and C which behaves > similarly to a transmission line. With ground, hence external C, absent, > it acts like a lumped L. The subject is 75m bugcatcher loading coils mounted on GMC pickups. How the heck does the ground get removed? > Important for what? No matter how long the coil or how many turns of the > wire, a small (in terms of wavelength) inductor won't act like a slow > wave structure ... A 75m bugcatcher coil is not small. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222661 of rec.radio.amateur.antenna From: Sum Ting Wong Subject: Re: Balloon lifted wire antenna? Message-ID: <065422lhn5bjoanha3jjnjbleo6jpfbh2v@4ax.com> References: Date: Thu, 23 Mar 2006 03:33:17 GMT On Wed, 22 Mar 2006 10:36:48 +0100, Deni wrote: >I'm going to have a go with a 3/8 wavelength (for 160M) wire, lifted by >a 2M helium balloon during the summer months. FWIW, I was down at Quartzsite, AZ for the "Quartzfest" campout in January and saw someone with a very nice helium balloon that looked like it would be ideal for supporting antennas. It wasn't being flown by one of the hams but by one of the off-roaders camped nearby so they could find their way back to their campsite. I asked where they got their balloon and they gave me this url: http://www.arizonaballoon.com/generic3.html The "ball" balloons look ideal for supporting a 1/4 /\ vertical for 160M. 73/ S.T.W. Article: 222662 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Current through coils Date: Wed, 22 Mar 2006 19:37:31 -0800 Message-ID: <12245vsp3rgb00c@corp.supernews.com> References: <121mh75g3ekkme9@corp.supernews.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <85ydnUdYMN0xMbzZnZ2dnUVZ_vednZ2d@adelphia.com> John Popelish wrote: > . . . > That's exactly the difference. But if you measure a single point, you > can't tell whether you are measuring a point on a traveling wave or a > standing wave. Agree? > There seems to be some confusion about just what a standing wave is. A standing wave is the result of, and the sum of, two or more traveling waves. There aren't points which are "on" one or the other. If you can separately measure or calculate the values of the traveling current waves at any point, you can add them to get the total current (what Cecil calls "standing wave current") at that point. If you add the traveling current waves at each point along the line and plot the amplitude of the sum (that is, of the total current) versus position, you see a periodic relationship between the amplitude and position. It's this relationship which is called a "standing wave". It's so called because its position relative to the line stays fixed. It's simply a graph of the total current (the sum of the traveling waves) vs. position. Roy Lewallen, W7EL Article: 222663 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <85ydnUdYMN0xMbzZnZ2dnUVZ_vednZ2d@adelphia.com> <1223dvop83mkq9a@corp.supernews.com> <12244tdjaher025@corp.supernews.com> Message-ID: Date: Thu, 23 Mar 2006 03:41:01 GMT Roy Lewallen wrote: > The coil in the EZNEC model on Cecil's web page acts just like we'd > expect an inductor to act. With ground present constituting a C, the > circuit acts like an L network made of lumped L and C which behaves > similarly to a transmission line. With ground, hence external C, absent, > it acts like a lumped L. (There are actually some minor differences, due > to imperfect coupling between turns and to coupling to the finite sized > external circuit.) The combination of L and C "act like" a transmission > line, just like any lumped L and C. And it doesn't care whether the load > is a whip or just lumped components. But the point is that the delay through the coil is somewhere between 40 degrees and 60 degrees. When you tried to measure the phase shift through a coil, you used standing wave current phase to make the measurement. Standing wave current phase is unchanging so you made a measurement blunder. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222664 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <85ydnUdYMN0xMbzZnZ2dnUVZ_vednZ2d@adelphia.com> <12245vsp3rgb00c@corp.supernews.com> Message-ID: <6UoUf.58578$H71.20962@newssvr13.news.prodigy.com> Date: Thu, 23 Mar 2006 03:48:18 GMT Roy Lewallen wrote: > A standing wave is the result of, and the sum of, two or more traveling > waves. There aren't points which are "on" one or the other. If you can > separately measure or calculate the values of the traveling current > waves at any point, you can add them to get the total current (what > Cecil calls "standing wave current") at that point. If you add the > traveling current waves at each point along the line and plot the > amplitude of the sum (that is, of the total current) versus position, > you see a periodic relationship between the amplitude and position. It's > this relationship which is called a "standing wave". It's so called > because its position relative to the line stays fixed. It's simply a > graph of the total current (the sum of the traveling waves) vs. position. And there's no such thing as current imbalance based on standing wave currents being different at each end of a loading coil. "Current imbalance" is a concept that doesn't apply to standing waves. "Phase rotation with position" is a concept that doesn't apply to standing waves. Standing wave current is NOT ordinary current. It is the superposition of two ordinary currents. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222665 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Current through coils Date: Wed, 22 Mar 2006 20:06:41 -0800 Message-ID: <12247mhls4oqmca@corp.supernews.com> References: <121mh75g3ekkme9@corp.supernews.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <85ydnUdYMN0xMbzZnZ2dnUVZ_vednZ2d@adelphia.com> <1223dvop83mkq9a@corp.supernews.com> <12244tdjaher025@corp.supernews.com> Correction: Roy Lewallen wrote: (Last paragraph) > Important for what? No matter how long the coil or how many turns of the > wire, a small (in terms of wavelength) inductor won't act like a slow > wave structure or an axial mode helical antenna. . . The word "diameter" should be added: > Important for what? No matter how long the coil or how many turns of > the wire, a small *diameter* (in terms of wavelength) inductor won't > act like a slow wave structure or an axial mode helical antenna. . . Roy Lewallen, W7EL Article: 222666 of rec.radio.amateur.antenna From: Butch Magee Subject: OOOooooohhhhhhhhhh, Get to my Question Date: Wed, 22 Mar 2006 22:28:25 -0600 Message-ID: <12248vhflrht441@corp.supernews.com> Cecil< QUIT talking with alll those kidz about sparks "n arks "n stuff whill i HAVE A VERY really very question on the board. You know, the one about the Wideband Folded Loop (WFL) 400.00 FROM RF-Systems. Will my thoughts work or whut! giddy-yupbapa mau-mau )cant remember where that came from, just enterred my head and has been plaqueing me for for days............... Butch KF5DE Article: 222667 of rec.radio.amateur.antenna From: Rick Frazier Subject: Re: Multiband Dipole Angles References: Message-ID: Date: Thu, 23 Mar 2006 04:39:17 GMT Troy Majors wrote: > What effect will the following have: > > both legs of the multiband dipole 60 to 65 feet up in the air cannot be in a > straight line, but one leg must vary from a true north-south diple to the > northeast at about a 35-40 degree angle from the other leg. Also, both legs > slant downward in a slight inverted-V configuration, probably about 20-25 > degrees. The feed line will come straight down at a 90 degree angle from > the dipole legs, but will then split the difference in its horizontal move > along the ground to the house. How much do I lose from all this compared to > a dipole with both legs straight in line, and the feedline 90 degrees from > the dipole both vertically and horizontally? > > All this is driven by the size of the lot, the placement of the trees in the > back and front yards, the direction and density of the various limbs off the > trees, and the level of my skill with a slingshot. I have the pilot ropes > in place but have not raised the antenna yet. Any advice before I commit to > this configuration? > > Thanks, > Troy > > Yeah, put it up, get on the air and enjoy... You probably wouldn't notice the differences in antenna patterning or gain, unless you have access to a really big test range and good evaluation equipment. You should, however, check the resonant frequencies after it's up, and adjust the length (the extra tails, if needed can hang straight down if needed without any reall effect on pattern). You've already got the hard part done, getting the support ropes in place. Agonizing over the minimal effect it has over a "perfect" antenna isn't worth the time. thanks --Rick AH7H Article: 222668 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Current through coils Date: Wed, 22 Mar 2006 23:03:52 -0800 Message-ID: <1224i2p9j0tr33d@corp.supernews.com> References: <121mh75g3ekkme9@corp.supernews.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <85ydnUdYMN0xMbzZnZ2dnUVZ_vednZ2d@adelphia.com> <1223dvop83mkq9a@corp.supernews.com> <12244tdjaher025@corp.supernews.com> John Popelish wrote: > Roy Lewallen wrote: > . . . > > In >> my modification to Cecil's EZNEC file I showed how the coil behaves >> the same with no antenna at all, just a lumped load impedance. As long >> as the load impedance and external C stay the same, the coil behavior >> stays the same. > > Excellent. As long as there is external C, the coil acts in a non > lumped way, regardless of whether its current passes to an antenna or a > dummy load. This is the same result you would get with any transmission > line, also, except that the C is inside the line, instead of all around it. No, the coil is acting in a lumped way whether the C is there or not. A combination of lumped L and lumped C mimics a transmission line over a limited range. But neither the L nor C is acting as more or less than a lumped component. All the "transmission line" properties I listed in my last posting for the LC circuit can readily be calculated by considering L and C to be purely lumped components. >> Well, not a "slow wave" transmission line. > > Its propagation is a lot slower than a normal transmission line based on > straight conductors, isn't it? There's more L per unit length than on an equal length line made with straight wire, so yes the propagation speed is slower. But there's nothing magic about that. A lumped LC circuit can be found to have exactly the same delay and other characteristics of a transmission line, and it can do it in zero length. > >> We shouldn't confuse an ordinary lumped LC transmission line >> approximation with a true slow wave structure such as a helical >> waveguide (next item). > > Heaven forfend. ;-) I am not clear on the difference. A slow wave structure is a type of waveguide in which the fields inside propagate relatively slowly. Ramo and Whinnery is a good reference, and I'm sure I can find others if you're interested. >> The propagation velocity of the equivalent transmission line is >> omega/sqrt(LC), so the speed depends equally on the series L and the >> shunt C. > > Per unit of length in the direction of propagation. Helical coils have > a lot of L in the direction of propagation, compared to straight wire > lines, don't they? Yes indeed, as discussed above. And as I said above, you can get plenty of delay from a lumped L and C of arbitrarily small physical size. > . . . >> So what can we conclude about inductors from this similar behavior? >> Certainly not that there's anything special about inductors >> interacting with traveling waves or that inductors comprise some kind >> of "slow wave structure". The duality comes simply from the >> fundamental equations which describe the nature of transmission lines, >> inductances, and capacitances. > > The question, I think is whether large, air core coils act like a single > inductance (with some stray capacitance) that has essentially the same > current throughout, or is a series of inductances with distributed stray > capacitance) that is capable of having different current at different > points, a la a transmission line. And the answer must be that it > depends on the conditions. At some frequencies, it is indistinguishable > from a lumped inductance, but at other frequencies, it is clearly > distinguishable. You have to be aware of the boundary case. Yes. It's a continuum, going from one extreme to the other. As Ian has pointed out several times, any theory should be able to transition from one to the other. The example Cecil posted on his web page was one for which the L could be modeled completely adequately as a lumped L, at least so far as its current input and output properties were concerned. Being a significant fraction of the antenna's total length, it of course does a substantial amount of radiating which a lumped model does not. >> Because the LC section's properties are identical to a transmission >> line's at one frequency, we have our choice in analyzing the circuit. >> We can pretend it's a transmission line, or we can view it as a lumped >> LC network. If we go back to the fundamental equations of each circuit >> element, we'll find that the equations end up exactly the same in >> either case. And the results from analyzing using each method are >> identical -- if not, we've made an error. > > But a continuous coil is not a series of discrete lumped inductances > with discrete capacitances between them to ground, but a continuous > thing. In that regard, it bears a lot of similarity to a transmission > line. But it has flux coupling between nearby turns, so it also has > inductive properties different from a simple transmission line. Which > effect dominates depends on frequency. Yes, that's correct. But if it's short in terms of wavelength, a more elaborate model than a single lumped inductance won't provide any different results. > >> The coil in the EZNEC model on Cecil's web page acts just like we'd >> expect an inductor to act. > > A perfect point sized inductor? I don't think so. Except for the radiation, yes. In what ways do you see it differing? > >> With ground present constituting a C, the circuit acts like an L >> network made of lumped L and C which behaves similarly to a >> transmission line. With ground, hence external C, absent, it acts like >> a lumped L. (There are actually some minor differences, due to >> imperfect coupling between turns and to coupling to the finite sized >> external circuit.) The combination of L and C "act like" a >> transmission line, just like any lumped L and C. And it doesn't care >> whether the load is a whip or just lumped components. > > I agree with the last sentence. The ones before that seem self > contradictory. First you say it acts just like an inductor, then you > say it acts like a transmission line. These things (in the ideal case) > act very differently. Let me try again. The combination of L and the C to ground act like a transmission line, just like a lumped LC acts like a transmission line. With the ground removed, there's nearly no C, so there's very little transmission-line like qualities. Of course you could correctly argue that there's still a tiny amount of C to somewhere and so you could still model the circuit as a transmission line. The equivalent transmission line would have very high impedance and a velocity factor very near one. Such a transmission line is difficult to distinguish from a plain inductor. >>. . . >> Important for what? No matter how long the coil or how many turns of >> the wire, a small (in terms of wavelength) inductor won't act like a >> slow wave structure or an axial mode helical antenna. > > But its propagation speed will be slower than it would be if the wire > were straight. don't know if that qualifies it for a "slow wave" line > or not. That's the third time for this. Sure. A theoretical lumped inductor and a theoretical lumped shunt capacitor can have a very slow propagation velocity, and with no physical length at all. I'm failing to see why this has some special relevance. >> This is for the same reason that a two inch diameter pipe won't >> perform as a waveguide at 80 meters -- there's not enough room inside >> to fit the field distribution required for that mode of signal >> propagation. There will of course be some point at which it'll no >> longer act as a lumped inductor but would have to be modeled as a >> transmission line. But this is when it becomes a significant fraction >> of a wavelength long. > > Why can't it be modeled as a transmission line before it is that long? > will you get an incorrect result, or is it just a convenience to model > it as a lumped inductor, instead? Hm, I tried to explain that, but obviously failed. You can model it either way. If you've done your math right, you'll get exactly the same answer, because you'll find that you're actually solving the same equations. >. . . Roy Lewallen, W7EL Article: 222669 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Current through coils Date: Wed, 22 Mar 2006 23:22:22 -0800 Message-ID: <1224j5f3hgauge9@corp.supernews.com> References: <121mh75g3ekkme9@corp.supernews.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <85ydnUdYMN0xMbzZnZ2dnUVZ_vednZ2d@adelphia.com> <12245vsp3rgb00c@corp.supernews.com> <6UoUf.58578$H71.20962@newssvr13.news.prodigy.com> John Popelish wrote: > > You two are so close to agreement. Standing waves have a current that > varies with position. The fact that the EZNEC simulation of a loading > coil shows differing current in a situation that is a fairly pure > standing wave situation (more energy bouncing up and down the antenna > than is radiating from it) means that the RMS current will vary along > the standing wave. And, since the simulation shows a different current > magnitude at the two ends of the coil, a significant part of a standing > wave cycle must reside inside the coil (more than the physical length > between the two ends of the coil would account for). No, you're misinterpreting what you're seeing. Imagine an LC L network with theoretically lumped series L and shunt C. If you look at the currents at the input and output of the perfect inductor, you'll find that they're exactly the same. If, however, you look at the currents in and out of the *network* you'll see that they're different, because of current going to ground through the C. And, as I said before, you can even pretend it's a transmission line and measure forward and reverse traveling waves and a standing wave ratio. But with zero length, there can be no standing waves inside the inductor. Yet the terminal characteristics of the network are the same as a transmission line. You don't need to imagine standing waves residing inside the inductor in the LC circuit, and you don't need to imagine them inside the inductor in Cecil's model, either. When you look at the currents reported by EZNEC for the model on Cecil's web page, the current at the top of the coil is the equivalent to the *network* current described above. It's the current flowing through the inductance minus the current being shunted to ground via the C between the coil and ground. You can tell just how much this is by looking at my modified model and subtracting the current going into the coil from ground from the current going into ground from the added wire. They're not the same -- the difference is the displacement current through the C >from the inductor to ground. When I removed the ground, you could then see the current flowing through the inductor, by itself, without the current being shunted off. And lo and behold, it's nearly the same at both ends of the inductor, showing that the inductor is behaving very much like a lumped L. Only in conjunction with the C to ground does the combination mimic a transmission line -- just like any other lumped LC circuit. Of course, at some length and/or poorness of interturn coupling, a coil will start behaving in a way we can't adequately model as a lumped L. But that's not the case here. > . . . Roy Lewallen, W7EL Article: 222670 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <85ydnUdYMN0xMbzZnZ2dnUVZ_vednZ2d@adelphia.com> <1223dvop83mkq9a@corp.supernews.com> <12244tdjaher025@corp.supernews.com> <12247mhls4oqmca@corp.supernews.com> Message-ID: Date: Thu, 23 Mar 2006 09:27:06 GMT Roy Lewallen wrote: > > Important for what? No matter how long the coil or how many turns of > > the wire, a small *diameter* (in terms of wavelength) inductor won't > > act like a slow wave structure or an axial mode helical antenna. . . So many words trying to avoid the real issue which is: What is the percentage of a wavelength occupied by a loading coil. It doesn't matter what the size of the coil is. In the real world, a loading coil occupies a certain percentage of a wavelength. For a small coil, that percentage will be small. For a large coil that percentage will be large. We have had to throw out your phase measurements using the phase of standing wave currents because that phase you used is unchanging whether in a wire or in a coil. Your phase measurements tell us zero information about the delay through a coil. That leaves us only with indirect measurements based on the self- resonant frequency of the coil in the mobile environment or the phase information left in the standing wave current amplitude over the 90 degree antenna. My self-resonant frequency measurements indicate that a 75m loading- coil occupies 40-60 degrees of a 360 degree wavelength. That's 11%-17% of a wavelength. Dr. Corum's papers agree with that estimate. Another way of estimating the percentage of the antenna occupied by the loading coil would be to plot the current segments from feedpoint to tip. Then draw a cosine wave on the same graph with 0 degrees at the feedpoint and 90 degrees at the tip. A rough estimate of the percentage occupied by the coil would be the slice of the cosine wave from the bottom of the coil to the top of the coil. Mere words are not going to change the percentage of a wavelength occupied by a real-world loading coil. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222671 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: OOOooooohhhhhhhhhh, Get to my Question References: <12248vhflrht441@corp.supernews.com> Message-ID: Date: Thu, 23 Mar 2006 09:28:46 GMT Butch Magee wrote: > Cecil< QUIT talking with alll those kidz about sparks "n arks "n stuff > whill i HAVE A VERY really very question on the board. You know, the > one about the Wideband Folded Loop (WFL) 400.00 FROM RF-Systems. Will > my thoughts work or whut! I apologize, Butch. I haven't had time to read it. It's 3:30AM and I'm getting ready to leave for spring break. I'll be back Monday. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222672 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <12234rh79jg535e@corp.supernews.com> <1143077128.011283.306270@v46g2000cwv.googlegroups.com> Message-ID: Date: Thu, 23 Mar 2006 09:34:04 GMT John Popelish wrote: > Oh poo. At current nodes charge piles up and spreads out, on > alternating half cycles. For one half cycle, the pile is positive, and > for the next it is negative. This is a basic transmission line > concept. If transmission lines had no shunt capacitance, there would be > no place to put this charge. But there is, so it is no problem. Whether > the transmission line is coax, twin line or a slow wave helix makes > little difference. The process is similar. Isn't this what you have > been arguing? If the forward traveling wave is equal in magnitude at both ends of the coil, there is no net storage of energy due to the forward traveling wave. If the reflected traveling wave is equal in magnitude at both ends of the coil, there is no net storage of energy due to the reflected traveling wave. Superposing those two waves still results in no net storage of energy. Sorry, got to hit the road. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222673 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <85ydnUdYMN0xMbzZnZ2dnUVZ_vednZ2d@adelphia.com> <1223dvop83mkq9a@corp.supernews.com> <12244tdjaher025@corp.supernews.com> Message-ID: Date: Thu, 23 Mar 2006 09:47:20 GMT John Popelish wrote: > The question, I think is whether large, air core coils act like a single > inductance (with some stray capacitance) that has essentially the same > current throughout, or is a series of inductances with distributed stray > capacitance) that is capable of having different current at different > points, a la a transmission line. And the answer must be that it > depends on the conditions. At some frequencies, it is indistinguishable > from a lumped inductance, but at other frequencies, it is clearly > distinguishable. You have to be aware of the boundary case. Dr. Corum says the boundary is 15 degrees, or 0.04 wavelength. Another place in his class notes he says that if 1/6 of a wavelength of wire is used to make the coil, the lumped-circuit model will NOT work. My 75m bugcatcher coil is more than 1/6 of a wavelength of wire. > But a continuous coil is not a series of discrete lumped inductances > with discrete capacitances between them to ground, but a continuous > thing. In that regard, it bears a lot of similarity to a transmission > line. But it has flux coupling between nearby turns, so it also has > inductive properties different from a simple transmission line. Which > effect dominates depends on frequency. Dr. Corum has a test equation to see if his velocity factor equation applies. The test is: 5*N*D^2/lamda(0) <= 1 where N is number of turns, D is the diameter of the coil, and lamda(0) is the self-resonant frequency. If this equation is satisfied, then equation (32) applies for velocity factor. For my 75m bugcatcher coil, the test number is 0.4 <= 1 and the velocity factor equation yields 0.0175. That's certainly a slow wave device. > But its propagation speed will be slower than it would be if the wire > were straight. don't know if that qualifies it for a "slow wave" line > or not. A velocity factor of 0.0175 for a 75m bugcatcher seems to qualify. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222674 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <85ydnUdYMN0xMbzZnZ2dnUVZ_vednZ2d@adelphia.com> <12245vsp3rgb00c@corp.supernews.com> Message-ID: Date: Thu, 23 Mar 2006 09:51:39 GMT John Popelish wrote: > If there is a standing wave on a wire, and you have a > tiny current transformer sensor you can slide along the wire, you can > measure the instantaneous current (or the RMS) at any point along the > wire. If the sensor sits at a single point and sees an AC current, you > have no way, from this one measurement, if this current is the result of > a standing wave (two oppositely traveling equal waves adding), or a > single traveling wave, or any combination of traveling waves of > different amplitudes. You know only the net current at that point. But if one it smart enough to slide the sensor up and down the wire and note the phase is fixed and unchanging, one knows he is dealing with a standing wave. >> If you add the traveling current waves at each point along the line >> and plot the amplitude of the sum (that is, of the total current) >> versus position, you see a periodic relationship between the amplitude >> and position. It's this relationship which is called a "standing >> wave". It's so called because its position relative to the line stays >> fixed. It's simply a graph of the total current (the sum of the >> traveling waves) vs. position. And that's all it is - the sum of two traveling waves. A standing wave has no separate existence of its own. It is an artifact of superposition. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222675 of rec.radio.amateur.antenna From: "David J Windisch" References: Subject: Re: Current through coils - BFD Message-ID: Date: Thu, 23 Mar 2006 09:57:04 GMT "BFD" ida "Before Final Decision", n'est ce pas? "Richard Clark" wrote in message news:mu7322hcinluakhvtib9t6l9a9104de8jj@4ax.com... > > Well, let's start with Yuri's emphasized and cogent assertion: > "The current in a typical loading coil in the shortened antennas BIGSNIP of a howler Article: 222676 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <85ydnUdYMN0xMbzZnZ2dnUVZ_vednZ2d@adelphia.com> <12245vsp3rgb00c@corp.supernews.com> <6UoUf.58578$H71.20962@newssvr13.news.prodigy.com> Message-ID: Date: Thu, 23 Mar 2006 09:59:03 GMT John Popelish wrote: > Standing waves have a current that > varies with position. The fact that the EZNEC simulation of a loading > coil shows differing current in a situation that is a fairly pure > standing wave situation (more energy bouncing up and down the antenna > than is radiating from it) means that the RMS current will vary along > the standing wave. And, since the simulation shows a different current > magnitude at the two ends of the coil, a significant part of a standing > wave cycle must reside inside the coil (more than the physical length > between the two ends of the coil would account for). And since a significant part of a standing wave cycle resides inside the coil, it occupies a non-negligible percentage of a wavelength. By every valid method, measured or calculated, a 75m bugcatcher coil occupies tens of degrees of a wavelength (out of 360 degrees). My best estimate is 60 degrees in a 75m mobile antenna. > In one case (the highest frequency one) the phase of the current even > reverses from one end of the coil to the other, as well as an amplitude > variation, indicating that a standing wave node occurs some where inside > the coil, and the two ends are on opposite ends of that node. If the > two currents had been equal, but 180 degrees out of phase, the node > would have been in the center of the coil. Yes, if a current node exists inside a coil, the standing wave currents are flowing into the coil at the same time from both ends and 1/2 cycle later they are both flowing out of the coil at the same time. Wonder how a lumped-circuit inductance handles that? :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 222677 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <12234rh79jg535e@corp.supernews.com> <1143077128.011283.306270@v46g2000cwv.googlegroups.com> <1143093225.723635.85530@t31g2000cwb.googlegroups.com> Message-ID: Date: Thu, 23 Mar 2006 10:10:23 GMT K7ITM wrote: > Cecil wrote, > "The forward current is equal at both ends of the coil. The reflected > current is equal at both ends of the coil." > > If that's really true, then the net current is precisely equal at both > ends of the coil. I was speaking above about the magnitudes only, not the phases. It was clear from the rest of my posting that was the assumption. The fact that you attempted to change the meaning by trimming is noted. So to be perfectly clear, here is my statement re-worded using a 45 degree phase shift through the coil. The forward current magnitude is equal at both ends of the coil. The reflected current magnitude is equal at both ends of the coil. At the bottom of the coil, the forward current is 1 amp at zero deg. At the bottom of the coil, the reflected current is 1 amp at zero deg. At the bottom of the coil, the standing wave current is 2 amps at zero deg. At the top of the coil, the forward current is 1 amp at -45 deg. At the top of the coil, the reflected current is 1 amp at +45 deg. At the bottom of the coil, the standing wave current is 1.4 amp at zero deg. I asked if you knew how to do phasor math but you trimmed out that phasor math part of my posting. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222678 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <12234rh79jg535e@corp.supernews.com> <1143077128.011283.306270@v46g2000cwv.googlegroups.com> <1143093705.598974.199250@i40g2000cwc.googlegroups.com> Message-ID: Date: Thu, 23 Mar 2006 10:20:12 GMT K7ITM wrote: > Cecil wrote, among other things, > "One amp of forward current is flowing into the coil and one > amp of forward current is flowing out of the coil. Charge is > balanced." > > Absolutely NOT! You said the phase difference between the two ends is > 45 degrees. Therefore, charge "input" and "output" is balanced ONLY > twice during a cycle, when the instantaneous currents are the same. No > phase need apply here: we're talking INSTANTANEOUS currents. Give us a break, Tom. Of course, we are *NOT* and never have been talking instantaneous currents. All currents ever discussed concerning this subject have been RMS currents. That's just your instantaneous strawman. Long term charge accumulation is averaged over many cycles. There is simply none of that because the traveling waves are not storing any net charge inside the coil. How can you get so desperate as to play such silly games? My statement obviously meant: One amp of RMS forward current is flowing into the coil and one amp of RMS forward current is flowing out of the coil. Average charge is balanced. Even though the standing wave current is different at each end of the coil, the average charge into and out of the coil is still balanced. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222679 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <85ydnUdYMN0xMbzZnZ2dnUVZ_vednZ2d@adelphia.com> <1223dvop83mkq9a@corp.supernews.com> <12244tdjaher025@corp.supernews.com> <1224i2p9j0tr33d@corp.supernews.com> Message-ID: Date: Thu, 23 Mar 2006 10:28:23 GMT Roy Lewallen wrote: > No, the coil is acting in a lumped way whether the C is there or not. That is a presupposition of the lumped-circuit model. You cannot use that to try to prove the validity of the lumped-circuit model. > A slow wave structure is a type of waveguide in which the fields inside > propagate relatively slowly. Ramo and Whinnery is a good reference, and > I'm sure I can find others if you're interested. My 75m bugcatcher coil has a velocity factor of 0.0175 calculated, 0.015 measured. That's a slow wave structure. > Yes indeed, as discussed above. And as I said above, you can get plenty > of delay from a lumped L and C of arbitrarily small physical size. Just as you can from an arbitrarily large 75m bugcatcher coil. No extra capacitance needed. > With the ground removed, there's nearly no C, so there's very little > transmission-line like qualities. You forgot to tell us how to remove the ground from my 75m bugcatcher antenna system mounted on my GMC pickup. > That's the third time for this. Sure. A theoretical lumped inductor and > a theoretical lumped shunt capacitor can have a very slow propagation > velocity, and with no physical length at all. I'm failing to see why > this has some special relevance. Because you reported zero phase shift through a real-world loading coil. Since standing wave current phase is unchanging, you blundered badly. The real question remains: What percentage of a wavelength does a 75m bugcatcher coil occupy in a 75m mobile antenna installation? The answer is tens of degrees. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222680 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <85ydnUdYMN0xMbzZnZ2dnUVZ_vednZ2d@adelphia.com> <12245vsp3rgb00c@corp.supernews.com> <6UoUf.58578$H71.20962@newssvr13.news.prodigy.com> <1224j5f3hgauge9@corp.supernews.com> Message-ID: Date: Thu, 23 Mar 2006 10:35:04 GMT Roy Lewallen wrote: > If, however, you look at the currents in > and out of the *network* you'll see that they're different, because of > current going to ground through the C. The main effect in a standing wave environment are the forward and reflected phasors rotating in opposite directions. The standing wave current is ZERO when those phasors are 180 degrees out of phase. The standing wave current is maximum when those phasors are in phase. "Current going to ground through the C" is not even required. > But with zero length, there > can be no standing waves inside the inductor. You keep saying stuff like this as if a zero length inductor actually existed in reality. Wake up, Roy, and smell the roses. That zero length inductor exists only in human minds. > When you look at the currents reported by EZNEC for the model on Cecil's > web page, the current at the top of the coil is the equivalent to the > *network* current described above. It's the current flowing through the > inductance minus the current being shunted to ground via the C between > the coil and ground. Huh? How do you explain the current at the top being greater than the current at the bottom of the coil? Is the coil sucking current >from the ground? -- 73, Cecil http://www.qsl.net/w5dxp Article: 222681 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <85ydnUdYMN0xMbzZnZ2dnUVZ_vednZ2d@adelphia.com> Message-ID: <0TuUf.4260$tN3.427@newssvr27.news.prodigy.net> Date: Thu, 23 Mar 2006 10:36:44 GMT Ian White GM3SEK wrote: > You see a larger picture of the whole antenna, so you can choose many > different ways to theorize about it. But your theory cannot be correct > if it requires that components behave in different, special ways > according to the way you happen to be thinking about it at the time. Inuendo devoid of any technical content, Ian? It is not my theory. It is the distributed network model which you apparently reject. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222682 of rec.radio.amateur.antenna Subject: Re: OOOooooohhhhhhhhhh, Get to my Question From: Doc Date: Thu, 23 Mar 2006 06:42:31 -0600 Message-ID: <1143117627_1535@sp6iad.superfeed.net> References: <12248vhflrht441@corp.supernews.com> Butch, > giddy-yupbapa mau-mau > )cant remember where that came from, just enterred my head > and has been plaqueing me for for days............... Statler Brothers - 'Doc Article: 222683 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <121mh75g3ekkme9@corp.supernews.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <85ydnUdYMN0xMbzZnZ2dnUVZ_vednZ2d@adelphia.com> <0TuUf.4260$tN3.427@newssvr27.news.prodigy.net> Message-ID: Date: Thu, 23 Mar 2006 12:59:28 GMT Ian White GM3SEK wrote: > Precisely and specifically NOT that! :-) "My theory"? It's not my theory. Components behaving differently? No. Special ways according to my thinking? Of course not. There's nothing special. The "special magic thinking" is yours in thinking that standing wave current is the same as traveling wave current. > If you cannot see that statement as a fundamental principle of > scientific logic, then I have run out of ways to tell you. I see your statement for exactly what it is, Ian, full of inuendo and ignorance of the nature of standing wave current. Have you no clue what func(kx)*func(wt) really means? >> It is not my theory. It is the distributed network >> model which you apparently reject. > > No, I reject your incorrect applications. You reject the distributed network analysis because you are completely technically ignorant of the nature of standing wave current. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222684 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <85ydnUdYMN0xMbzZnZ2dnUVZ_vednZ2d@adelphia.com> <12245vsp3rgb00c@corp.supernews.com> <6UoUf.58578$H71.20962@newssvr13.news.prodigy.com> <1224j5f3hgauge9@corp.supernews.com> <1143113220.180021.272500@e56g2000cwe.googlegroups.com> Message-ID: <2exUf.49743$F_3.9045@newssvr29.news.prodigy.net> Date: Thu, 23 Mar 2006 13:17:50 GMT w8ji@akorn.net wrote: > That's utter nonsense Cecil, and why people aren't buying into your > misconceived theories. Sorry, Tom, that's distributed network analysis, something you and others seem to be totally ignorant of and confused by. I get emails every week from people who are buying into the distributed network analysis. Otherwise, they are forced to accept your magical thinking about reality. > A two-terminal network that transforms impedance, now there's a > concept! It isn't a two-terminal network. It is a single-wire transmission line over ground. It has forward and reflected waves working against ground, similar to a two-wire transmission line. > An inductor behaves exactly the same way in or out of your so-called > standing wave environment. It follows the same rules all the time. Quoting Dr. Corum again: "There are no standing waves [allowed] on a lumped element circuit component. (In fact, lumped-element circuit theory inherently employs the cosmological presupposition that the speed of light is infinite, as every EE sophmore should know.)" "Lumped circuit theory fails because it's a theory whose presuppositions are inadequate. Every EE in the world was warned of this in their first sophmore circuits course." Tom, where did you attend your sophmore EE classes? > Since your theory says otherwise, it has to be wrong. It is the distributed network theory, Tom, developed to handle just such cases of failure of the lumped-element model. Both models work in some instances. The distributed network model works when the lumped-element model fails. > Wave theory is just another way of analyzing a complex system. It > doesn't change how things inside the system behave. Exactly! But lumped-circuit theory changes how things inside the system behave when standing waves are present. One can observe its magical effects in your explanations. Unfortunately, it is not supposed to change anything. When a model tries to change the laws of physics, it's time to move to a more power model that doesn't. Bottom line: By every valid measurement and calculation, a 75m bugcatcher coil occupies roughly 60% of a mobile antenna. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222685 of rec.radio.amateur.antenna From: "Dale Parfitt" References: <1143078002.731378.198740@g10g2000cwb.googlegroups.com> <1143112714.314930.111790@t31g2000cwb.googlegroups.com> Subject: Re: V Beam, do they work? Message-ID: <2gxUf.15833$gD4.4913@trnddc05> Date: Thu, 23 Mar 2006 13:19:58 GMT wrote in message news:1143112714.314930.111790@t31g2000cwb.googlegroups.com... > > Dale Parfitt wrote: >> wrote in message >> news:1143078002.731378.198740@g10g2000cwb.googlegroups.com... >> > I've been modeling V beams off and on for a few years now, and never >> > can seem to get one that has useful gain. >> > >> > Has anyone seen a successful model anyplace of a two or three wave V >> > with good gain?? >> > >> > 73 Tom >> > >> Hi Tom, >> I have a model of a 5 wavelength 24MHz Vee beam in AO- I can send the >> file >> if it is useful to you. AO reports 11dBi free space gain. Included angle >> appears to be 44 degrees. > > I don't have AO Dave, so a description will work. > > That sounds like the problem I am seeing. With a 3-5 WL long V, I have > about the same gain as a three element Yagi. But I'll still try to > model your antenna with 5wl legs and 44 degree angle. Thanks. > Hi Tom et al, This is from the AO library: F=24.94 The vertex is at the origin: 0,0 X,Y of 1st leg is 185.44', -74.92' #12 wire X,Y of 2nd leg is 185.44', 74.92' #12 wire Fed at the origin and modeled in free space AO reports Z= 255- J706 Forward gain= 11.34dBi F/B 2.70dB Hope this is useful, Dale W4OP Article: 222686 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <_5iUf.29$163.18@fe08.lga> <1143077338.694612.238920@z34g2000cwc.googlegroups.com> <_3oUf.58565$H71.18677@newssvr13.news.prodigy.com> <1143113778.370901.113800@j33g2000cwa.googlegroups.com> Message-ID: Date: Thu, 23 Mar 2006 13:43:46 GMT w8ji@akorn.net wrote: > You claim a bug cather coil has "an electrical length at 4MHz of ~60 > degrees". That concept is easily proven false, just like the claim a > short loaded antenna is "90-degree resonant". Both can be shown to be > nonsense pictures of what is happening. Well, I've been challenging you to do just that for weeks now and so far, nothing. Please note the contradiction between your statement above which says an antenna doesn't have to be 90 degrees long to be resonant and your statement below which says it does. Would you please make up your mind? > Assume I have a 30 degree long antenna. If the loading inductor is 60 > electrical degrees long, I could move it anyplace in that antenna and > have a 90 degree long antenna. This again demonstrates your misconceptions. Please pay attention this time. When my 75m bugcatcher coil is configured as a base-loaded coil with a 7 foot whip, it occupies ~60 degrees of antenna. The 7 foot whip occupies ~10 degrees of the antenna. The total length is only ~70 degrees, not 90 degrees. That 90 degrees is just your strawman and you even contradicted yourself above. The antenna doesn't have to be 90 degrees long. What has to happen is for (Vfor+Vref)/(Ifor+Iref) to be resistive at the feedpoint. There are many possibilities for that in antennas not 90 degrees long. I gave one such example possibility weeks ago. Perhaps you missed it. I haven't measured the number of degrees occupied by a center- loaded 75m bugcatcher coil. Since the inductance of the center-loaded coil must be increased when moved from the base to the center, it would occupy more of the antenna at the center than it does at the base for the same resonant frequency. The 70uH 75m bugcatcher coil occupies ~60 degrees when installed at the base. For the same resonant frequency and same length for the rest of the antenna, a center-loaded coil would need about double that reactance, making it about 1.4 times the size of the base-loaded coil. So I would estimate that the center-loaded coil is occupying ~80 degrees of the antenna, much closer to a total of 90 degrees than the base-loaded version. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222687 of rec.radio.amateur.antenna From: Gene Fuller Subject: Re: Current through coils References: <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <12234rh79jg535e@corp.supernews.com> <1143077128.011283.306270@v46g2000cwv.googlegroups.com> <1143093705.598974.199250@i40g2000cwc.googlegroups.com> Message-ID: Date: Thu, 23 Mar 2006 14:31:13 GMT Cecil, Well, I guess it's back to the math books for me. I mistakenly thought that currents described by cos(kz-wt) and cos(kz).cos(wt) would be considered "instantaneous" currents. If they're really RMS, well . . . I am curious about one thing, however. It would seem that all of this "averaging", "RMS", and "net" is a bit inconsistent with digging into a distributed network problem, which you insist is the only valid description. Everything can vary in time and space in a distributed network. Certainly these consolidating functions are useful for a general overview, but how can you learn anything about the details of a complex system by averaging and netting? 73, Gene W4SZ Cecil Moore wrote: > > Give us a break, Tom. Of course, we are *NOT* and never have been > talking instantaneous currents. All currents ever discussed concerning > this subject have been RMS currents. That's just your instantaneous > strawman. Long term charge accumulation is averaged over many cycles. > There is simply none of that because the traveling waves are not storing > any net charge inside the coil. How can you get so desperate as to play > such silly games? > > My statement obviously meant: One amp of RMS forward current is flowing > into the coil and one amp of RMS forward current is flowing out of the > coil. Average charge is balanced. > > Even though the standing wave current is different at each end of the > coil, the average charge into and out of the coil is still balanced. Article: 222688 of rec.radio.amateur.antenna From: "Caveat Lector" References: <220320061901558586%artie.m@gNOSPAMmail.com> Subject: Re: Balloon lifted wire antenna? Message-ID: Date: Wed, 22 Mar 2006 20:37:53 -0800 Balloon Antenna URL's http://www.qsl.net/g4vgo/index.htm http://www.hard-core-dx.com/nordicdx/antenna/special/baloon.html And a lawn chair balloon flight (;-) http://home.earthlink.net/~quade/lawnchair.html -- CL -- I doubt, therefore I might be ! "artie" wrote in message news:220320061901558586%artie.m@gNOSPAMmail.com... > In article , Deni > wrote: > >> I'm going to have a go with a 3/8 wavelength (for 160M) wire, lifted by >> a 2M helium balloon during the summer months. The first 40' of wire will >> be supported vertically by a fibre glass mast then the remaining 156' by >> the balloon. I have a ground plane in place already and will use a >> manual tuner at the base to 50 ohm coax, I expect to use this on other >> bands besides Top band. What is a good type of wire to use, obviously >> flexible, not too heavy but good copper content, or would electric fence >> cord (with woven in stainless steel strands) be too lossy? looking for >> any tips advice etc. >> >> 73, Deni >> F5VJC > > Been there, done that, lived to tell the tale... Ended up putting the > wire spool in a metal can and feeding the entire can, so the wire on > the spool wasn't some weird inductor. > > As other OPs point out, be aware of your local aviation authority > rules. In the U.S., flying things above a few hundred feet can garner > the wrong kind of attention. > > In more rural areas, you may garner attention from people with rifles. > > Discharge off the end of the wire tends to disagree with thin balloon > material; a few meter stringer of nonconductive line is a *good* idea > (or have a backup balloon and a backup supply of gas). > > Helium is for pansies. Use hydrogen; it won't leak as fast (really -- > those heliums are solitary little sneaky bastards and will get out of > anything, while hydrogens are diatomic and tend to stick around > longer). > > Above all, have fun! > > -- > Namaste-- Article: 222689 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <1142734010.632531.71060@v46g2000cwv.googlegroups.com> <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <_5iUf.29$163.18@fe08.lga> <1143077338.694612.238920@z34g2000cwc.googlegroups.com> <_3oUf.58565$H71.18677@newssvr13.news.prodigy.com> <1143113778.370901.113800@j33g2000cwa.googlegroups.com> Subject: Re: Current through coils Message-ID: Date: Thu, 23 Mar 2006 11:12:54 -0500 wrote in message > > Let's focus on one thing at a time. > > You claim a bug cather coil has "an electrical length at 4MHz of ~60 > degrees". That concept is easily proven false, just like the claim a > short loaded antenna is "90-degree resonant". Both can be shown to be > nonsense pictures of what is happening. > > Assume I have a 30 degree long antenna. If the loading inductor is 60 > electrical degrees long, I could move it anyplace in that antenna and > have a 90 degree long antenna. > > We all know that won't happen, so what is it you are really trying to > say? > > 73 Tom > OK lets get me some educating here. I understand that, say quarter wave resonant vertical (say 33 ft at 40m) has 90 electrical degrees. Is that right or wrong? The current distrubution on said (full size) vertical is one quarter of the wave of 360 deg. which would make it 90 degrees. Max current is at the base and then diminishes towards the tip in the cosine function down to zero. Voltage distribution is just opposite, min at the base, feed point and max at the tip. EZNEC modeling shows that to be the case too. Is that right or wrong? If we stick them end to end and turn horizontal, we get dipole, which then would be 180 deg. "long" or "180 degrees resonant". If not, what is the right way? If I insert the coil, say about 2/3 up (at 5 ft. from the bottom) the shortened vertical, I make the coil size, (inductance, phys. dimensions) such that my vertical will shrink in size to 8 ft tall and will resonate at 7.87 MHz. I learned from the good antenna books that this is still 90 electrical "resonant" degrees. Maximum of current is at the feed point, minimum or zero at the tip. If you stick those verticals (resonant) end to end and horizontal, you get shortened dipole, with current distribution equal to 180 degrees or half wave. Max current at the feed point, minima or zero at the tips. (RESONANT radiator) How many electrical degrees would that make? How do you arrive at that? Why is this a nonsense? Can we describe "pieces" or segments of the radiator as having proportional amount of degrees corresponding to their physical length, when excited with particular frequency? If I can be enlightened about this, we can go then to the next step. Answers, corrections please. Yuri, K3BU Article: 222690 of rec.radio.amateur.antenna From: Butch Magee Subject: This is the one I was referring to....... Date: Thu, 23 Mar 2006 10:58:06 -0600 Message-ID: <1225ksv6su9hlf1@corp.supernews.com> http://www.rys.nl.wfl.htm How do I build this thing, I can't find schematics anywhere...............Butch KF5DE Article: 222691 of rec.radio.amateur.antenna From: Butch Magee Subject: Lets try this one Date: Thu, 23 Mar 2006 11:05:07 -0600 Message-ID: <1225la45rqjthe5@corp.supernews.com> http://rys.nl/wfl.html this oughta wurk Article: 222692 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Current through coils References: <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <85ydnUdYMN0xMbzZnZ2dnUVZ_vednZ2d@adelphia.com> <12245vsp3rgb00c@corp.supernews.com> <6UoUf.58578$H71.20962@newssvr13.news.prodigy.com> <1224j5f3hgauge9@corp.supernews.com> <1143113220.180021.272500@e56g2000cwe.googlegroups.com> Message-ID: <89BUf.41342$_S7.23762@newssvr14.news.prodigy.com> Date: Thu, 23 Mar 2006 17:45:40 GMT John Popelish wrote: > w8ji@akorn.net wrote: > >> A two-terminal network that transforms impedance, now there's a >> concept! > > > (My opinion follows, please correct me. Dang, I should put that in my > sig.) > > In reality, there is no such thing as a two terminal network, unless one > of those terminals is grounded. For all other cases, there is an > unavoidable implied ground terminal that covers all the stray > capacitance of the device. > > So the bug catcher coil is recognized as a 3 terminal device, with > ground being the third terminal. It can be modeled as a pi, T or > transmission line structure, as long as you want to understand what to > quantify it at only one frequency (or a narrow band), and the choice is > arbitrary. If you are concerned with modeling a large frequency range > (that goes well past the first self resonance), one of those models (or > a more complicated one) will be superior. You fellows lack imagination. As long as you're trying to morph a coil into a transmission line, why not just imagine it as a shorted stub? There's more than one way to make an inductive reactance. 73, Tom Donaly, KA6RUH Article: 222693 of rec.radio.amateur.antenna From: "Yuri Blanarovich" Subject: Current across the antenna loading coil - from scratch Message-ID: Date: Thu, 23 Mar 2006 12:50:32 -0500 OK, I have been accused of being wrong, claiming that current across the antenna loading coil is or can be different at its ends. I and "my camp" say that we are seeing somewhere 40 to 60 % less current at the top of the coil, than at the bottom, in other words, significant or noticeable drop. W8JI and "his camp" are claiming it can't be so, current through the coil has to be the same or almost the same, with no significant drop across the loading coil. Let's start the fresh thread and trace step by step where I went wrong. Just reminder that we are talking typical situations, as for example real 40 m (or 80 m) mobile whip with loading coil about 2/3 up the radiator. We are talking about resonant electrical quarter wave monopole. We are talking about standing wave RF current that can be measured with RF ammeter and is shown and plotted in modeling programs like EZNEC. Here we go: wrote in message > > Let's focus on one thing at a time. > > You claim a bug cather coil has "an electrical length at 4MHz of ~60 > degrees". That concept is easily proven false, just like the claim a > short loaded antenna is "90-degree resonant". Both can be shown to be > nonsense pictures of what is happening. > > Assume I have a 30 degree long antenna. If the loading inductor is 60 > electrical degrees long, I could move it anyplace in that antenna and > have a 90 degree long antenna. > > We all know that won't happen, so what is it you are really trying to > say? > > 73 Tom > OK lets get me some educating here. I understand that, say quarter wave resonant vertical (say 33 ft at 40m) has 90 electrical degrees. Is that right or wrong? The current distrubution on said (full size) vertical is one quarter of the wave of 360 deg. which would make it 90 degrees. Max current is at the base and then diminishes towards the tip in the cosine function down to zero. Voltage distribution is just opposite, min at the base, feed point and max at the tip. EZNEC modeling shows that to be the case too. Is that right or wrong? If we stick them end to end and turn horizontal, we get dipole, which then would be 180 deg. "long" or "180 degrees resonant". If not, what is the right way? If I insert the coil, say about 2/3 up (at 5 ft. from the bottom) the shortened vertical, I make the coil size, (inductance, phys. dimensions) such that my vertical will shrink in size to 8 ft tall and will resonate at 7.87 MHz. I learned from the good antenna books that this is still 90 electrical "resonant" degrees. Maximum of current is at the feed point, minimum or zero at the tip. If you stick those verticals (resonant) end to end and horizontal, you get shortened dipole, with current distribution equal to 180 degrees or half wave. Max current at the feed point, minima or zero at the tips. (RESONANT radiator) How many electrical degrees would that make? How do you arrive at that? Why is this a nonsense? Can we describe "pieces" or segments of the radiator as having proportional amount of degrees corresponding to their physical length, when excited with particular frequency? If I can be enlightened about this, we can go then to the next step. Answers, corrections please. Yuri, K3BU Article: 222694 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <_5iUf.29$163.18@fe08.lga> <1143077338.694612.238920@z34g2000cwc.googlegroups.com> <_3oUf.58565$H71.18677@newssvr13.news.prodigy.com> <1143113778.370901.113800@j33g2000cwa.googlegroups.com> Subject: Re: Current through coils Message-ID: Date: Thu, 23 Mar 2006 13:02:43 -0500 Richard and everybody, Let's try again from scratch, fresh, I will try to go step by step, so there are no ambiguities, twists and turns to each own's la-la land. Cecil is on well deserved break, so I am am on my own, stuck on whatever it might be. I will not continue, unless there is an agreement at each point, I go sloooow, for the benefit of mine and others who duntgetit. The "camp" think is to signify two groups claiming the different behavior of the current in the antenna loading coil. No intent to punish anyone. Please go to the new thread that I started. "Current across the antenna loading coil - from scratch" If needed I will post pictures on my web site, unless there is a way to do it here. Thank you! Yuri, K3BU.us Article: 222695 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: This is the one I was referring to....... References: <1225ksv6su9hlf1@corp.supernews.com> Message-ID: <5g7bf3-7nu.ln1@p400bob.personal.cox.net> Date: Thu, 23 Mar 2006 12:54:27 -0600 Hi Butch The cebik URL I posted gives you dimensions and values for a full length one. I'd suggest that since it is such a wide band device terminated in a resistor, choose some arbitary value like 600 ohms, feed it via a balun transformer and see what happens! Take the manufacturers description and photo to work out the wire lengths. What I am mainly getting at is being such a wideband antenna with resistive loading, the dimensions wont be critical. Cheers Bob VK2YQA Butch Magee wrote: > > > http://www.rys.nl.wfl.htm > > > How do I build this thing, I can't find schematics > anywhere...............Butch KF5DE Article: 222696 of rec.radio.amateur.antenna Subject: Re: OOOooooohhhhhhhhhh, Get to my Question From: Doc Date: Thu, 23 Mar 2006 13:52:02 -0600 Message-ID: <1143143341_2021@sp6iad.superfeed.net> References: <12248vhflrht441@corp.supernews.com> <1143117627_1535@sp6iad.superfeed.net> Doc wrote: ...and yes, Elvira. - 'Doc Article: 222697 of rec.radio.amateur.antenna From: David Subject: Any good antenna design software Message-ID: Date: Fri, 24 Mar 2006 00:02:53 GMT I am looking for antenna design software. Initially I purchased EZNEC and downloaded a couple of other programs but realized these are analysis only programs that are great to check performance and optimize once you have a design. I managed to find a variety of freeware design programs but they were not very extensive (an mostly DOS programs that sometimes crashed my graphics). My preference is for a Windows based design environment that provides some templates as starting points for a variety of antenna styles (Yagi, LPDA, Verticals). I would like to be able to set up the program with the materials I have available and some performance criteria and it would output element lengths, spacing, suitable matching (or give input impedance etc). I can then enter this design into EZNEC or MMANA to analyse performance. Thanks in advance if you can point me to suitable software I can purchase. Regards David Article: 222698 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Current through coils Date: Thu, 23 Mar 2006 17:38:19 -0800 Message-ID: <1226jcd1ocf3g84@corp.supernews.com> References: <121mh75g3ekkme9@corp.supernews.com> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <85ydnUdYMN0xMbzZnZ2dnUVZ_vednZ2d@adelphia.com> <12245vsp3rgb00c@corp.supernews.com> <6UoUf.58578$H71.20962@newssvr13.news.prodigy.com> John Popelish wrote: > . . . > Of course, it can't. But a lumped LC network made of perfect, ideal > components can be constructed that mimic the terminal conditions of the > coil in question to any degree of accuracy desired. The caveat is that > you may not explore much of a frequency range if you expect this > idealized model to remain a good mimic. At another frequency, you have > to rebuild it to copy the effects at that frequency. The broader the > frequency range of such a model, the more complexity it must have. Yes, but you can use an arbitrarily large number of sections, each with a small amount of L and C, and mimic a transmission line to any desired degree, over any frequency range you want. And all with zero physical size in the theoretical case, and arbitrarily small physical size in the practical case. In the limit of an infinite number of sections of vanishingly small L and C each, you arrive at the general equations for a transmission line, valid at all frequencies. The point I'm trying to make is that you don't need any particular physical size or any particular length of wire to make something that behaves like a transmission line to any degree of accuracy. Roy Lewallen, W7EL Article: 222699 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Current across the antenna loading coil - from scratch Date: Thu, 23 Mar 2006 17:44:06 -0800 Message-ID: <1226jn6onq2uj28@corp.supernews.com> References: <5pOdnWnjAutrvL7Z4p2dnA@comcast.com> Dave wrote: > . . . > The practical application deals with the efficiency of the antenna. Is > that tuned 15 degree long antenna a 12.5 ampere degree antenna; or, is > it a 10.218 ampere degree antenna? [That's approximately a difference of > 1 dB in antenna performance.] > . . . I believe you're comparing the field strengths from two antennas both driven by the same current. If you drive them with the same power, a more fair comparison, you'll find a negligible difference in field strength. Efficiency is another issue, solely related to losses in the antennas. Without knowing what those losses might be, we can't say anything about the relative efficiency. In practice it'll probably be extremely closely the same also. Roy Lewallen, W7EL Article: 222700 of rec.radio.amateur.antenna From: Buck Subject: Re: Balloon lifted wire antenna? Message-ID: References: Date: Thu, 23 Mar 2006 21:54:32 -0500 On Wed, 22 Mar 2006 10:36:48 +0100, Deni wrote: >I'm going to have a go with a 3/8 wavelength (for 160M) wire, lifted by >a 2M helium balloon during the summer months. The first 40' of wire will >be supported vertically by a fibre glass mast then the remaining 156' by >the balloon. I have a ground plane in place already and will use a >manual tuner at the base to 50 ohm coax, I expect to use this on other >bands besides Top band. What is a good type of wire to use, obviously >flexible, not too heavy but good copper content, or would electric fence >cord (with woven in stainless steel strands) be too lossy? looking for >any tips advice etc. > >73, Deni >F5VJC Don't forget to add a bleeder resistor so the static buildup won't destroy your radio. -- 73 for now Buck N4PGW Article: 222701 of rec.radio.amateur.antenna From: "Sal M. Onella" References: <12248vhflrht441@corp.supernews.com> <1143117725.873311.311820@g10g2000cwb.googlegroups.com> Subject: Re: OOOooooohhhhhhhhhh, Get to my Question Message-ID: Date: Thu, 23 Mar 2006 20:43:42 -0800 wrote in message news:1143117725.873311.311820@g10g2000cwb.googlegroups.com... > > Butch Magee wrote: > > Cecil< QUIT talking with alll those kidz about sparks "n arks "n stuff > > whill i HAVE A VERY really very question on the board. You know, the > > one about the Wideband Folded Loop (WFL) 400.00 FROM RF-Systems. Will > > my thoughts work or whut! > > > > giddy-yupbapa mau-mau > > )cant remember where that came from, just enterred my head > > and has been plaqueing me for for days............... > > > > Butch KF5DE > > Elvira? My heart's on fire. Article: 222702 of rec.radio.amateur.antenna From: "k" References: <121phe846j8pdd1@corp.supernews.com> Subject: Re: antenna theory for idiots? Message-ID: <6RKUf.14335$%d.2983@tornado.socal.rr.com> Date: Fri, 24 Mar 2006 04:46:58 GMT Is this an explanation of the term 'capture area' I hear a lot of hams use. regards, Jer As a 'rule of thumb' the captured signal power in small loops is proportional to the area enclosed by the loop. Twice the area = twice the power (3 dB). The typical dimensions given for these loops allow them to be used on either 160M or 80M -- and as you have surmised, the loop can be larger for 160M only. 73, Gary K9AY _________ Subject: [Antennaware] Shielded loop receive antennas. > In the ARRL antenna handbook (and repeated elsewhere) is a design for > a 160m shielded rx loop antenna with 5ft square sides. > > Can anyone advise me how the strength of the recovered signal would > change if the loop was made bigger. By using low-capacity coax I > think I could still resonate a loop that has 7ft square sides. This > would very nearly double the **AREA** of the loop, I would like to > understand how this would affect the received signal. > > Any thoughts would be appreciated. > > 73, Article: 222703 of rec.radio.amateur.antenna From: "Hal Rosser" References: <12248vhflrht441@corp.supernews.com> Subject: Re: OOOooooohhhhhhhhhh, Get to my Question Message-ID: Date: Fri, 24 Mar 2006 00:51:47 -0500 "Butch Magee" wrote in message news:12248vhflrht441@corp.supernews.com... > Cecil< QUIT talking with alll those kidz about sparks "n arks "n stuff > whill i HAVE A VERY really very question on the board. You know, the > one about the Wideband Folded Loop (WFL) 400.00 FROM RF-Systems. Will > my thoughts work or whut! > > giddy-yupbapa mau-mau > )cant remember where that came from, just enterred my head > and has been plaqueing me for for days............... > > Butch KF5DE its oom papa oom papa mau mau El vire ah Mah harts on fire -uh 4 elvire-uh oom papa oom papa mau mau Article: 222704 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Current through coils Date: Fri, 24 Mar 2006 00:28:59 -0800 Message-ID: <1227bed4qaf0t71@corp.supernews.com> References: <121mh75g3ekkme9@corp.supernews.com> <9HUTf.14734$bn3.8252@bgtnsc04-news.ops.worldnet.att.net> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <85ydnUdYMN0xMbzZnZ2dnUVZ_vednZ2d@adelphia.com> <1223dvop83mkq9a@corp.supernews.com> <12244tdjaher025@corp.supernews.com> <1224i2p9j0tr33d@corp.supernews.com> <9oidndktkuKTQ7_ZnZ2dnUVZ_vudnZ2d@adelphia.com> John Popelish wrote: > Roy Lewallen wrote: >> John Popelish wrote: >>> Roy Lewallen wrote: > > You keep going back to how lumped components can mimic actual > distributed ones (over a narrow frequency range). I get it. I have no > argument with it. But why do you keep bringing it up? We are talking > about a case that is at least a border line distributed device case. I > am not interested in how it can be modeled approximately by lumped, > ideal components. I am interested in understanding what is actually > going on inside the distributed device. I'm sorry I haven't explained this better. If we start with the inductor in, say, the example antenna on Cecil's web page, we see that the magnitude of current at the top of the inductor is less than at the bottom of the inductor. Cecil has promoted various theories about why this happens, mostly involving traveling wave currents and "replacement" of "electrical degrees" of the antenna. He and others have given this as proof that the current at the two ends of an inductor are inherently different, regardless of its physical size. My counter argument goes something like this: 1. If we substitute a lumped component network for the antenna, there are no longer traveling waves -- along the antenna at least -- and no number of "missing electrical length" for the inductor to replace. Or if there is, it's "replacing" the whole antenna of 90 degrees. Yet the currents in and out of the inductor are the same as they were before. I feel this is adequate proof of the invalidity of the "replacement" and traveling wave arguments, since I can reproduce the same results with the same inductor without either an antenna or traveling waves. This is shown in the modified EZNEC file I posted. 2. The argument that currents are inherently different at the ends of an inductor is shown to be false by removing the ground in the model I posted and replacing it with a wire. Doing so makes the currents nearly equal. 3. Arguments have then been raised about the significance of the wire and inductor length, and various theories traveling waves and standing waves within the length of the coil. Let's start with the inductor and no ground, with currents nearly equal at both ends. Now shrink the coil physically by shortening it, changing its diameter, introducing a permeable core, or whatever you want, until you get an inductance that has the same value but is infinitesimal in physical size. For the whole transition from the original to the lumped coil, you won't see any significant(*) change in terminal characteristics, in its behavior in the circuit, or the behavior of the whole circuit. So I conclude there's no significant electrical difference in any respect between the physical inductor we started with and the infinitesimally small lumped inductor we end up with. And from that I conclude that any explanation for how the original inductor worked must also apply to the lumped one. That's why I keep bringing up the lumped equivalents. We can easily analyze the lumped circuit with elementary techniques; the same techniques are completely adequate to fully analyze the circuit with real inductor and capacitance to ground. (*) I'm qualifying with "significant" because the real inductor doesn't act *exactly* like a lumped one. For example, the currents at the ends are slightly different due to several effects, and the current at a point along the coil is greater than at either end due to imperfect coupling among turns. But the agreement is close -- very much closer than the alternative theories predict (to the extent that they predict any quantitative result). > >>> The question, I think is whether large, air core coils act like a >>> single inductance (with some stray capacitance) that has essentially >>> the same current throughout, or is a series of inductances with >>> distributed stray capacitance) that is capable of having different >>> current at different points, a la a transmission line. And the >>> answer must be that it depends on the conditions. At some >>> frequencies, it is indistinguishable from a lumped inductance, but at >>> other frequencies, it is clearly distinguishable. You have to be >>> aware of the boundary case. >> >> >> Yes. It's a continuum, going from one extreme to the other. As Ian has >> pointed out several times, any theory should be able to transition >> from one to the other. > > Or start with a less simplified theory that covers all cases, so you > don't have to decide when to switch tools. That's fine, too. Will Cecil's theory explain the behavior of a lumped constant circuit? Or everywhere along the transition between the physical inductor and lumped circuit I described above? > > The example Cecil posted on his web page was one for >> which the L could be modeled completely adequately as a lumped L, at >> least so far as its current input and output properties were concerned. > > (if you add to that model, the appropriate lumped capacitors at the > appropriate places) No. The inductor itself can be adequately modeled as a lumped inductor without any capacitors at all. When you add ground to the model, you have to add the equivalent shunt C to the lumped model. The C isn't a property of the inductor itself; it's the capacitance between the inductor and ground. This difference is the source of confusion and misunderstanding about the current -- the current we see at the top of the inductor is the current exiting the inductor minus the current going via the shunt C to ground. It's not due to a property of the inductor itself. We're seeing the *network* current, not the inductor current. Removing the ground lets us see the inductor current by itself. > >> Being a significant fraction of the antenna's total length, it of >> course does a substantial amount of radiating which a lumped model >> does not. > Another reason to avoid that model, unless you are just looking for the > least amount of math to get an approximation. But computation has > gotten very cheap. The problem is that it obscures what's happening -- we can no longer easily tell which effects are due to the radiation, which are due to the capacitance, and which are inherent properties of inductance unless we separately analyze separate simplified circuits (as I did with EZNEC). And that's really what the whole disagreement has been about. Effects due to shunt capacitance have been claimed to be inherent properties of all inductors, and elaborately crafted theories developed to attempt to explain it. If all you want is numbers, they're plenty easy to get without the programmer needing to have the slightest understanding of what's happening. And he will have learned nothing he can apply to other situations. Distributed analysis is just fine, but it should predict the same coil currents with the antenna replaced by lumped components. And it should predict nearly equal currents in the inductor ends when ground is removed. And it should predict the same results when the coil and the shunt C to ground are replaced by lumped components. Because that's what really happens. My simplified lumped component analysis does all this. A rigorous solution of the fundamental equations for distributed networks does this also -- EZNEC does its calculations with just such equations and reaches the correct conclusions. But I don't believe that Cecil's theories and methods provide the correct results in all these cases. > . . . > A lumped inductor has no stray capacitance. Those also have to be added > to the model, before the effect would mimic the real coil (neglecting > radiation). By removing the ground in the model on my web site, I found that a lumped inductor mimics the real inductor very well without any C. Of course, to model an inductor close to ground requires adding a shunt C. Modeling an inductor connected to a resistor would require adding a resistor to the model. But we shouldn't confuse what the inductor is contributing to the performance of the circuit with what the other components are. And that confusion has been common here. > . . . > But in the real world, the capacitance is always there. It varies, > depending on the location of the coil, but it never approaches zero. It can get insignificantly small, as in the modified model. But that's really beside the point. The point is that the shunt C isn't an inherent property of the inductor, and the current difference between the top and bottom of an electrically short coil is due to the current flowing through the external shunt C, however big or small it is. It's not due to waves bouncing around inside the coil or painstakingly winding their way turn by turn from one end to the other, or by any inherent and fixed property of the inductor or the antenna it's connected to. Roy Lewallen, W7EL Article: 222705 of rec.radio.amateur.antenna From: "Dale Parfitt" References: <1143078002.731378.198740@g10g2000cwb.googlegroups.com> <9uf5221s02so80rn0pssm94jtrfn79pg1l@4ax.com> <1143164190.846521.171860@t31g2000cwb.googlegroups.com> <1143207103.880628.220750@j33g2000cwa.googlegroups.com> Subject: Re: V Beam, do they work? Message-ID: Date: Fri, 24 Mar 2006 14:15:07 GMT wrote in message news:1143207103.880628.220750@j33g2000cwa.googlegroups.com... > > Dave wrote: >> Something does not make sense!! >> >> There HAS to be a difference in gain between two antennas IF their HPBW >> are different. Isn't it the case that the narrower beam has to have >> higher gain? > > No. > > First problem, the V beam has more loss. Probably because of the very > long current path through conductors. > > Second problem, large sidelobes that rob power > >I would only add that one of the sidelobes in the Vee beam- off the rear- >is almost as large as the main lobe, being typically only 2-3dB down from >the forward lobe. Dale W4OP Article: 222706 of rec.radio.amateur.antenna From: Gene Fuller Subject: Re: Current through coils References: <1142804860.185346.321020@t31g2000cwb.googlegroups.com> <7h0Uf.56741$H71.4420@newssvr13.news.prodigy.com> <9s443VIJXQIEFA+7@ifwtech.co.uk> <12234rh79jg535e@corp.supernews.com> <1143077128.011283.306270@v46g2000cwv.googlegroups.com> <1143093705.598974.199250@i40g2000cwc.googlegroups.com> Message-ID: Date: Fri, 24 Mar 2006 14:28:32 GMT Cecil, You can be the master of brevity, at least when it serves your purposes. You might take a look at the entire sentence rather than clip out the portion that sets the context. "Certainly these consolidating functions are useful for a general overview, but how can you learn anything about the details of a complex system by averaging and netting?" By the way, "steady-state analysis" has nothing whatsoever to do with averaging. Steady-state simply means the system does not have a defined starting time. There are no remaining startup transients. It cannot be determined whether operation started one second ago or one year ago. Steady-state does not mean DC, averaged, or RMS. 73, Gene W4SZ Cecil Moore wrote: > Gene Fuller wrote: > >> ... how can you learn anything about the details of a complex system >> by averaging and netting? > > > Because the conservation of energy principle is about > averaging and netting. Because steady-state analysis > is about averaging and netting. Because engineers > have 200 years of averaging and netting behind us > to prove that it works. When you try to track an > individual electron's velocity and position, guess > what happens? Article: 222707 of rec.radio.amateur.antenna From: Buck Subject: Re: Reducing number of elements in this design Message-ID: References: <0e3Tf.9944$dy4.8651@news-server.bigpond.net.au> Date: Fri, 24 Mar 2006 09:30:23 -0500 On Sun, 19 Mar 2006 02:20:44 GMT, David wrote: >Hi, > >Would someone be able to advise me how I would calculate new dimensions >to scale the 9-Element Yagi >(described at http://www.qsl.net/ve3cvg/antennas/900b/index.html) >down to say a 4 or 5 element version. FWIW, if you can't model the antenna and change the design, try looking for someone else's design similar enough to make the change. You may just try reducing the number of elements according to your desired maximum length without much consequence. Good luck BUck n4pgw -- 73 for now Buck N4PGW Article: 222708 of rec.radio.amateur.antenna From: Buck Subject: Re: SWR Tells Me?? Message-ID: <4k0822pr8pp31dukckhb7s8n4joh4keqel@4ax.com> References: Date: Fri, 24 Mar 2006 09:30:29 -0500 On Mon, 20 Mar 2006 08:12:51 -0700, jimbo wrote: >OK, I have a new 2 meter j-pole antenna installed in my 3rd floor >attic. I have 50 feet of LMR240 coax running to the basement. I >measure SWR at the following frequencies on simplex. > >144.2 2.5 >145.2 2.4 >146.2 2.3 >147.2 1.9 >147.9 1.7 > >Can I conclude that the antenna is electrically short for the 2 meter >band? > >Thanks for any insight, jimbo That or it is mis-matched -- 73 for now Buck N4PGW Article: 222709 of rec.radio.amateur.antenna From: Buck Subject: Re: V Beam, do they work? Message-ID: <8k0822die4ing7rtpoheb5n44hbuf0okam@4ax.com> References: <1143078002.731378.198740@g10g2000cwb.googlegroups.com> Date: Fri, 24 Mar 2006 09:30:33 -0500 I was just reading about them in the antenna handbook. The v-beam is better than a dipole and is directional, but the same wire bent half-way out to make a rombic seems to add more gain. you might look into it. Buck N4PGW On 22 Mar 2006 17:40:02 -0800, w8ji@akorn.net wrote: >I've been modeling V beams off and on for a few years now, and never >can seem to get one that has useful gain. > >Has anyone seen a successful model anyplace of a two or three wave V >with good gain?? > >73 Tom -- 73 for now Buck N4PGW Article: 222710 of rec.radio.amateur.antenna From: Buck Subject: Re: Attic antenna: rotator upside-down work? Message-ID: References: Date: Fri, 24 Mar 2006 09:38:16 -0500 > > BB> Will an antenna rotator like a Radio Shack or Channel Master work if > BB> hung upside-down from a roof beam, or should I try to come up with a > BB> way to secure it to the attic floor? > > Do you have a break-down of the assembly of the rotor? If there are no bearings when held upside down, you may damage the rotor by hanging it that way. Buck -- 73 for now Buck N4PGW Article: 222711 of rec.radio.amateur.antenna From: "Caveat Lector" References: <121phe846j8pdd1@corp.supernews.com> <6RKUf.14335$%d.2983@tornado.socal.rr.com> Subject: Re: Capture Area (was antenna theory for idiots?) Message-ID: Date: Fri, 24 Mar 2006 06:57:21 -0800 Here is a site for examples of capture areas of antennas http://www.sommerantennas.com/gain.html -- CL -- I doubt, therefore I might be ! "k" wrote in message news:6RKUf.14335$%d.2983@tornado.socal.rr.com... > Is this an explanation of the term 'capture area' I hear a lot of hams > use. > > regards, Jer > > As a 'rule of thumb' the captured signal power in small loops is > proportional to the area enclosed by the loop. Twice the area = twice > the > power (3 dB). > > The typical dimensions given for these loops allow them to be used on > either > 160M or 80M -- and as you have surmised, the loop can be larger for 160M > only. > > 73, Gary > K9AY > _________ > > Subject: [Antennaware] Shielded loop receive antennas. > > >> In the ARRL antenna handbook (and repeated elsewhere) is a design for >> a 160m shielded rx loop antenna with 5ft square sides. >> >> Can anyone advise me how the strength of the recovered signal would >> change if the loop was made bigger. By using low-capacity coax I >> think I could still resonate a loop that has 7ft square sides. This >> would very nearly double the **AREA** of the loop, I would like to >> understand how this would affect the received signal. >> >> Any thoughts would be appreciated. >> >> 73, > > Article: 222712 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Capture Area (was antenna theory for idiots?) Date: Fri, 24 Mar 2006 09:15:08 -0800 Message-ID: <1228a8tt916thca@corp.supernews.com> References: <121phe846j8pdd1@corp.supernews.com> <6RKUf.14335$%d.2983@tornado.socal.rr.com> You can also find many postings explaining capture area by doing a groups.google.com search of this newsgroup for the phrase "capture area". I've explained it here several times. Roy Lewallen, W7EL Caveat Lector wrote: > Here is a site for examples of capture areas of antennas > > http://www.sommerantennas.com/gain.html > Article: 222713 of rec.radio.amateur.antenna From: "W. Watson" Subject: Antenna Phase (Kraus)--Interferometry with Two Antennas Message-ID: <0aXUf.6445$x94.4064@newsread1.news.pas.earthlink.net> Date: Fri, 24 Mar 2006 18:48:28 GMT I was browsing through Antennas by Kraus, second ed., looking for something that might explain how two antennas separated by a distance D would have a resolution as the same as an antenna of size D, and hit upon some methods for computing radiation patterns. I'm not all that familiar with the methodology, but think it might be worthwhile exploring. I'm not all that knowledgeable about antenna theory, but was stumped by the introduction of antenna phase. He computes the patterns for several pairs of isotropic antennas separated by a distance d. There are several cases, which involve fixed or differences in phase and amplitude he considers, Chap. 4, sect. 4.2. Can anyone make the idea of phase dependency for an antenna, particularly an isotropic antenna (or whatever), a little more practical or real? Early on he talks about the phase delta being a function of (theta, phi) according to a typical Kraus 3-D view of this material. A nice abstraction, but I need something a little more concrete*. Of course, maybe my statement above about D is simpler to *prove* (not hand wave) than wading through this material. * I just noticed section 3-17 has some material on phase. Maybe that'll work. Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA) (121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time) Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet -- "Nature invented space so that everything didn't have to happen at Princeton." -- Martin Rees, Britain's Royal Astronomer, in a lecture at Princeton Web Page: Article: 222714 of rec.radio.amateur.antenna From: Butch Magee Subject: Re: OOOooooohhhhhhhhhh, Get to my Question Date: Fri, 24 Mar 2006 13:38:33 -0600 Message-ID: <1228i421r97vm3e@corp.supernews.com> References: <12248vhflrht441@corp.supernews.com> <1143117725.873311.311820@g10g2000cwb.googlegroups.com> Sal M. Onella wrote: > wrote in message > news:1143117725.873311.311820@g10g2000cwb.googlegroups.com... > >>Butch Magee wrote: >> >>>Cecil< QUIT talking with alll those kidz about sparks "n arks "n stuff >>>whill i HAVE A VERY really very question on the board. You know, the >>>one about the Wideband Folded Loop (WFL) 400.00 FROM RF-Systems. Will >>>my thoughts work or whut! >>> >>>giddy-yupbapa mau-mau >>>)cant remember where that came from, just enterred my head >>>and has been plaqueing me for for days............... >>> >>>Butch KF5DE >> >>Elvira? > > > My heart's on fire. > > Yep, an oldie and a goodie. Drove me nuts till I found out. Thanks Sal Butch Article: 222715 of rec.radio.amateur.antenna From: Butch Magee Subject: Re: OOOooooohhhhhhhhhh, Get to my Question Date: Fri, 24 Mar 2006 13:41:11 -0600 Message-ID: <1228i8vq26k169a@corp.supernews.com> References: <12248vhflrht441@corp.supernews.com> Hal Rosser wrote: > "Butch Magee" wrote in message > news:12248vhflrht441@corp.supernews.com... > >>Cecil< QUIT talking with alll those kidz about sparks "n arks "n stuff >>whill i HAVE A VERY really very question on the board. You know, the >>one about the Wideband Folded Loop (WFL) 400.00 FROM RF-Systems. Will >>my thoughts work or whut! >> >>giddy-yupbapa mau-mau >>)cant remember where that came from, just enterred my head >>and has been plaqueing me for for days............... >> >>Butch KF5DE > > its > oom papa oom papa mau mau > El vire ah > Mah harts on fire -uh 4 elvire-uh > oom papa oom papa mau mau > > > Yes, yea verily that is it!! I was literaly going nuts with that ditty running through my head.....but I got it now. Thanks, Butch Article: 222716 of rec.radio.amateur.antenna From: Michael Coslo Subject: Re: which is best? Date: Fri, 24 Mar 2006 15:23:31 -0500 Message-ID: References: Frank wrote: > "RB" wrote in message > news:iJkUf.578$Pe.103@bignews6.bellsouth.net... >> Well, I'm still getting tripped up in my terms. Not doing too well, here. >> >> What I'm looking for is max low angle radiation comparison of the two. > > The vertical, should have a far better low angle performance, although > four radials is probably inadequate to minimize ground absorbtion. Better to s that the vertical will put out more of it's energy at low angles. That makes a difference. Another thing to consider is that the vertical will take a whole lot longer to install than the dipole. Those radials can be a real pain in the back! The way my thinking has been shifting recently, I would suggest that people - a lot of people - think of the radiation pattern of an antenna as some sort of narrow blob that shoots off the thing at the "maximum angle". Trouble is, all antennas radiate at all angles. Some just better than others. Before condemning a dipole as not usable for DX because of its radiation angle, we should probably compare it to the angle of that vertical. Then look at just how many db difference there is between the two (all else being equal). And of course, as I have been finding out, which one does best at any given moment (let's define best as the highest signal level at the receiver) is going to change from moment to moment. I haven't gone to transmitting differences yet - 73 de Mike KB3EIA - > The inclusion of a loading coil does little or nothing to effect the > radiation efficiency. Article: 222717 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: What kind of antenna is this? Date: Fri, 24 Mar 2006 16:22:05 -0800 Message-ID: <122939i4qtju335@corp.supernews.com> References: <1143244911.442365.111790@z34g2000cwc.googlegroups.com> That's a collinear array, of a type sometimes called a Franklin antenna. It's very hard to estimate the gain, because even when constructed perfectly, the velocity factor of the coax prevents the inside and outside from both being the ideal length. And at that frequency, very small imperfections in building technique can have a major impact on the gain. But it should be a fun project and it might give noticeable gain over a quarter wave monopole. Roy Lewallen, W7EL KG0WX wrote: > http://wireless.gumph.org/content/4/3/011-mini-wireless-antenna.html > > The author calls it a sector antenna but I'm sure I've seen it in ham > applications but with another name. > > Also, can anyone quote me a dbi gain figure (@2.4ghz) for this? > > Thanks for the help! > > Ken KG0WX > Article: 222718 of rec.radio.amateur.antenna From: "Stargatesg1" References: <1143244911.442365.111790@z34g2000cwc.googlegroups.com> Subject: Re: What kind of antenna is this? Message-ID: Date: Sat, 25 Mar 2006 00:25:52 GMT It looks like a collinear style antenna to me. It should have decent gain. -- RoD KD0XX PG-6-29404 "KG0WX" wrote in message news:1143244911.442365.111790@z34g2000cwc.googlegroups.com... > > http://wireless.gumph.org/content/4/3/011-mini-wireless-antenna.html > > The author calls it a sector antenna but I'm sure I've seen it in ham > applications but with another name. > > Also, can anyone quote me a dbi gain figure (@2.4ghz) for this? > > Thanks for the help! > > Ken KG0WX > Article: 222719 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Capture Area (was antenna theory for idiots?) Message-ID: <9o5922h62tupb9b7kj5lvg91ud5i64r1i4@4ax.com> References: <121phe846j8pdd1@corp.supernews.com> <6RKUf.14335$%d.2983@tornado.socal.rr.com> Date: Sat, 25 Mar 2006 01:09:06 GMT On Fri, 24 Mar 2006 06:57:21 -0800, "Caveat Lector" wrote: >Here is a site for examples of capture areas of antennas > >http://www.sommerantennas.com/gain.html Are you recommending it? Is the following statement from the page correct? "Note: Antenna B has only half the capture area of antenna A and is therefore able to "catch" only 50 percent of the electromagnetic field; e.g., 50mV, compared to 100 mV/50 Ohms. This means 6dB less gain for antenna B in comparison to antenna A." -- Article: 222720 of rec.radio.amateur.antenna From: Butch Magee Subject: Re: Lets try this one Date: Fri, 24 Mar 2006 20:24:13 -0600 Message-ID: <12299slb8c8iu6e@corp.supernews.com> References: <1225la45rqjthe5@corp.supernews.com> Butch Magee wrote: > http://rys.nl/wfl.html > > this oughta wurk No it didn't good heavens! No No, Good Cecil, I'm going direct to you Cecil, you have to answer the question (s) Article: 222721 of rec.radio.amateur.antenna From: Butch Magee Subject: I need help Cecil Date: Fri, 24 Mar 2006 20:41:05 -0600 Message-ID: <4424ADC1.9050803@cableone.net> (as usual, I'm in great need) I have great problems in trying to post a photo/webpage to the group to help identify and discover dimentions to the "Wideband Folded Loop" that is somewhat described in the artical by RF-Systems Inc. Cecil, if you would do a google search on this statement "WFL Folded Loop Antenna", it will bring up the aformentioned artical and photograph. Upon printing the artical out, you will note that the web site is posted in the lower left hand of the page as is normal, however, if you enter that site it will send you to some off the wall site having nothing to do with antennas. Now, grab your wireless laptop, hop on your hog and enjoy your hunt for my benefit. Article: 222722 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Capture Area (was antenna theory for idiots?) Date: Fri, 24 Mar 2006 18:48:11 -0800 Message-ID: <1229bre2hd2pi16@corp.supernews.com> References: <121phe846j8pdd1@corp.supernews.com> <6RKUf.14335$%d.2983@tornado.socal.rr.com> <1143252897.745883.44290@v46g2000cwv.googlegroups.com> <0aCdnVWxsrAsN7nZRVn-sw@adelphia.com> What information are you looking for, capture area or effective height? Capture area determines how many watts you'll get into a conjugately matched load connected to the antenna. Effective height determines how many volts you'll get from an open circuited antenna. The two aren't directly related. For more information about the two topics, do a groups.google.com search for postings I've made on those topics in this newsgroup. As I've posted here quite a number of times before, the capture area of a lossless infinitesimally short dipole is very nearly as great as that of a half wave dipole, in their most favored directions. (The difference is about 10%, and it's due to the slight pattern shape difference caused by different current distributions). So except for loss the capture area of a ferrite rod antenna is within 10% of that of a dipole. But loss in a ferrite rod antenna will reduce the capture area considerably. If you're interested in knowing how much power you can get from a ferrite rod, then, what you need to know is its efficiency, which is a function of wire length, number of turns, and the antenna feedpoint impedance. I don't have the time right now to work it out for you. The effective height of a ferrite rod antenna is approximately: (2 * pi * mueff * N * A) / lambda where mueff = effective relative permeability of the rod (mainly a function of rod length) N = number of turns A = rod cross sectional area lambda = wavelength Roy Lewallen, W7EL John Popelish wrote: > w8ji@akorn.net wrote: >>> Caveat Lector wrote: >>> >>>> Here is a site for examples of capture areas of antennas >>>> >>>> http://www.sommerantennas.com/gain.html >> >> >>> John Popelish wrote: >>> Have you got a link to a similar site that covers ferrite rod antennas? >> >> >> I hope this question isn't taken the wrong way, but why would you want >> a similar site? That one is terrible for accuracy. The poor fellow who >> wrote that page doesn't even know what capture area is. > > I meant a site that addressed (correctly, one would hope) that concept > of capture area for rod antennas. > >> Wouldn't it be better to find a totally different type of site, one >> that at least has some technical accuracy? > > Okay, I'll take one of those. :-) > Article: 222723 of rec.radio.amateur.antenna From: "J. Mc Laughlin" Subject: Re: V Beam, do they work? Date: Fri, 24 Mar 2006 22:20:08 -0500 Message-ID: <1229di3ihv4gu3b@corp.supernews.com> References: <1143078002.731378.198740@g10g2000cwb.googlegroups.com> Dear Tom: It appears that you are investigating a slopping, V-beam with a feed point at about 90 meters and an operating frequency of, say, 1.82 MHz. When first used some 80 years ago, V-beams were horizontal (or, alternatively, entirely in a vertical plane). Two more 90 meter poles are not likely to be in the picture. The good news is that you are apparently interested in a narrow range of frequencies. That is good news because aligning the lobes with their changing polarization and orientation over a significant bandwidth is like composing something to compete with Mozart. Even using one frequency, it is a bear to get a slopping V to do one's bidding. I would limit lengths to integer multiples of 0.5L that could fit your farm. I would optimize a single, end fed wire (over ground) and in the process find a narrow range of lengths that look promising and that fit your site. Then add, and drive, the second wire. Iteration is called for. I would use a figure of merit that is the gain at a TOA of something like 30 degrees. Kraus, even in the first edition, presents several approximate equations to optimize a horizontal rhombic. They may give a little guidance. I think I read a Technical Report in the mid 60s on measurements of a sloping V put out by either NBS or ESSA. I seem not able to put my finger on it just now. As mentioned, the difficulty with sloping wires is finding a "good" bore-site addition of fields from the two wires when those fields are, to a first approximation, in the shape of cones with changing polarization. It is more easy with horizontal wires. If I live long enough to retire from teaching, this is a type of project that would be interesting to investigate. But I only have 42 years in and my good wife is certain that I could not stand the pace of retirement. Do let us know what you come up with. Good luck. 73, Mac N8TT Two side notes: My friend, HS and University classmate, and great DXer W8TWA has used a set of sloping V-beams on HF to good effect. -- As you know better than almost anyone, one needs a height in the neighborhood of 2L to get serious signals from a horizontally polarized antenna at the lower TOAs used for DX. You may find that your best sloping V-beam has a strong vertically polarized component in the main beam.