Inverted-L (was OT: Vertical antenna)
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Re: Inverted-L (was OT: Vertical antenna)
 
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I hope people doesn´t learn from this statement.
IMO this is as far from logic one can get. /Jim ------ On 2010-12-21 02:27, Don Wilhelm wrote: > > The ground conductivity in my area is not the greatest, so I have > accepted the logical consequences of that fact. > > 73, > Don W3FPR > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Guy, K2AV
I just have one question: What is grass?
--- On Mon, 12/20/10, Guy Olinger K2AV <[hidden email]> wrote: > > Many people are adopting a construction technique as > primary over > performance considerations, e.g. lay out wire and hold them > down with > lawn staples and let the grass grow up around them, holding > them in > suspension OVER the dirt, rather than notching them DOWN > INTO the > dirt. Grass supported bare wire radials will exhibit tuned > characteristics and a higher velocity factor than buried > bare radials. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: Inverted-L (was OT: Vertical antenna)
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In reply to this post by Jan Erik Holm
I suspect that Don was referring to the fact that poor ground conductivity affected his low angle performance, and that is absolutely true. There isn't a thing he or anyone else can do to change the far field effects of poor ground. He can add lots of radials, buried or otherwise, to improve feedpoint losses, but none of that has any effect whatsoever on the far field pattern. 73, Dave Ab7E On 12/20/2010 9:54 PM, Jan Erik Holm wrote: > I hope people doesn´t learn from this statement. > IMO this is as far from logic one can get. > /Jim > ------ > On 2010-12-21 02:27, Don Wilhelm wrote: >> The ground conductivity in my area is not the greatest, so I have >> accepted the logical consequences of that fact. >> >> 73, >> Don W3FPR >> > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: Inverted-L (was OT: Vertical antenna)
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In reply to this post by n7ws
It's that ugly green stringy stuff some people use to hide their beautiful brown dirt so that nobody tries to steal it. Dave, AB7E QTH not far from N7WS On 12/20/2010 10:37 PM, Wes Stewart wrote: > I just have one question: What is grass? > > --- On Mon, 12/20/10, Guy Olinger K2AV<[hidden email]> wrote: > >> Many people are adopting a construction technique as >> primary over >> performance considerations, e.g. lay out wire and hold them >> down with >> lawn staples and let the grass grow up around them, holding >> them in >> suspension OVER the dirt, rather than notching them DOWN >> INTO the >> dirt. Grass supported bare wire radials will exhibit tuned >> characteristics and a higher velocity factor than buried >> bare radials. Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: Inverted-L (was OT: Vertical antenna)
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In reply to this post by Guy, K2AV
Guy,
OK, I missed by a factor of 10. I am using 2 elevated radials per band, and the physical direction is such the pairs are horizontally opposed - that should reduce the radiation from the radials to zero (or nearly so). I first cut the radials 15% longer than the "formula" would indicate, and used my MFJ259B to determine the actual (X=0.00) resonance point. By changing the lentgth of the radial (one at a time), I was able to comee with a working antenna for 160, 80, and 40. While my antenna works well fot me, it is not a universal solution. 73, Don W3FPR On 12/20/2010 10:15 PM, Guy Olinger K2AV wrote: > 15 ohms miscellaneous in series with 32 ohm radiation resistance, only > 3%? Don't you mean 30%? > > What were the lengths of the elevated radials and how many? > > 73, Guy. > > On Mon, Dec 20, 2010 at 8:27 PM, Don Wilhelm<[hidden email]> wrote: >> Dave, >> >> If you read the radial tuning procedure in Low-Band DXing, you will find >> that it "all comes out in the wash". Yes, your statements are correct, >> and in fact that is how I did mine. Although I did not resonate my >> vertical monopole against any ground plane - I simply cut the lengths to >> what was stated in the article, and then cut each radial to resonate >> with that particular length of the "monopole". If the result was >> slightly "off-center fed", so be it, the impedance and the resonance >> point obtained were a good match for 50 ohm coax, and I left it at that. >> >> OK, so the ideal impedance of a vertical antenna is 32 ohms - I got >> closer to 50 ohms which indicates a 15 ohm loss in signal efficiency. >> It matches my feedline nicely, and I an willing to accept the the 3% >> loss in efficiency that represents. >> >> The ground conductivity in my area is not the greatest, so I have >> accepted the logical consequences of that fact. >> >> 73, >> Don W3FPR >> >> >> On 12/20/2010 8:06 PM, David Gilbert wrote: >>> "I personally would not consider elevated radials that are non-resonant" >>> >>> >>> I guess I'm having a difficult time with that comment. You can have a >>> resonant system without the elevated radials themselves being >>> "resonant" ... i.e, any two of them acting like a resonant dipole. If >>> the elevated radials are shorter than a 1/4 wavelength, all that is >>> required is that the vertical section be a little longer than a 1/4 >>> wavelength to compensate. If the radials are longer than a 1/4 >>> wavelength, the vertical section needs to be shorter than a 1/4 >>> wavelength for resonance. >>> >>> Elevated radials are kind of like the lower half of a vertical 1/2 >>> wavelength dipole except that it is "fanned out" for symmetry, and if >>> the radials are longer or shorter than half of a 1/2 wavelength dipole >>> the feedpoint simply behaves similarly to an off-center fed dipole. You >>> can prove this to yourself with EZNEC ... start with a vertical section >>> longer than 1/4 wavelength and see what length radials you need to have >>> a resonant feedpoint. Then do the same thing with different lengths of >>> vertical sections and see the effect on radiation pattern. I can tell >>> you that it isn't a direct function of radial resonance. >>> >>> I could be wrong, but I don't see any need at all for the radials to be >>> "resonant" on their own. You want system resonance and generally >>> speaking, for radiation effectiveness you want as long a vertical >>> section as you can manage. You might want to choose a vertical section >>> somewhat longer than a 1/4 wavelength and radials correspondingly >>> shorter than a 1/4 wavelength in order to take advantage of that >>> "off-center feed" aspect I mentioned in order to get a 50 ohm match. >>> >>> The only situation where resonant radials might be required is if you're >>> trying to decouple whatever is on the other side of the radials. In >>> that case, the radials act like a choke to keep current on the feedpoint >>> side of the resonant radials. You can see that effect with EZNEC as well. >>> >>> 73, >>> Dave AB7E >>> >> ______________________________________________________________ >> Elecraft mailing list >> Home:http://mailman.qth.net/mailman/listinfo/elecraft >> Help:http://mailman.qth.net/mmfaq.htm >> Post:mailto:[hidden email] >> >> This list hosted by:http://www.qsl.net >> Please help support this email list:http://www.qsl.net/donate.html >> Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: Inverted-L (was OT: Vertical antenna)
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In reply to this post by Guy, K2AV
Guy,
OK, I missed by a factor of 10. I am using 2 elevated radials per band, and the physical direction is such the pairs are horizontally opposed - that should reduce the radiation from the radials to zero (or nearly so). I first cut the radials 15% longer than the "formula" would indicate, and used my MFJ259B to determine the actual (X=0.00) resonance point. By changing the lentgth of the radial (one at a time), I was able to comee with a working antenna for 160, 80, and 40. While my antenna works well fot me, it is not a universal solution. 73, Don W3FPR On 12/20/2010 10:15 PM, Guy Olinger K2AV wrote: > 15 ohms miscellaneous in series with 32 ohm radiation resistance, only > 3%? Don't you mean 30%? > > What were the lengths of the elevated radials and how many? > > 73, Guy. > > On Mon, Dec 20, 2010 at 8:27 PM, Don Wilhelm<[hidden email]> wrote: >> Dave, >> >> If you read the radial tuning procedure in Low-Band DXing, you will find >> that it "all comes out in the wash". Yes, your statements are correct, >> and in fact that is how I did mine. Although I did not resonate my >> vertical monopole against any ground plane - I simply cut the lengths to >> what was stated in the article, and then cut each radial to resonate >> with that particular length of the "monopole". If the result was >> slightly "off-center fed", so be it, the impedance and the resonance >> point obtained were a good match for 50 ohm coax, and I left it at that. >> >> OK, so the ideal impedance of a vertical antenna is 32 ohms - I got >> closer to 50 ohms which indicates a 15 ohm loss in signal efficiency. >> It matches my feedline nicely, and I an willing to accept the the 3% >> loss in efficiency that represents. >> >> The ground conductivity in my area is not the greatest, so I have >> accepted the logical consequences of that fact. >> >> 73, >> Don W3FPR >> >> >> On 12/20/2010 8:06 PM, David Gilbert wrote: >>> "I personally would not consider elevated radials that are non-resonant" >>> >>> >>> I guess I'm having a difficult time with that comment. You can have a >>> resonant system without the elevated radials themselves being >>> "resonant" ... i.e, any two of them acting like a resonant dipole. If >>> the elevated radials are shorter than a 1/4 wavelength, all that is >>> required is that the vertical section be a little longer than a 1/4 >>> wavelength to compensate. If the radials are longer than a 1/4 >>> wavelength, the vertical section needs to be shorter than a 1/4 >>> wavelength for resonance. >>> >>> Elevated radials are kind of like the lower half of a vertical 1/2 >>> wavelength dipole except that it is "fanned out" for symmetry, and if >>> the radials are longer or shorter than half of a 1/2 wavelength dipole >>> the feedpoint simply behaves similarly to an off-center fed dipole. You >>> can prove this to yourself with EZNEC ... start with a vertical section >>> longer than 1/4 wavelength and see what length radials you need to have >>> a resonant feedpoint. Then do the same thing with different lengths of >>> vertical sections and see the effect on radiation pattern. I can tell >>> you that it isn't a direct function of radial resonance. >>> >>> I could be wrong, but I don't see any need at all for the radials to be >>> "resonant" on their own. You want system resonance and generally >>> speaking, for radiation effectiveness you want as long a vertical >>> section as you can manage. You might want to choose a vertical section >>> somewhat longer than a 1/4 wavelength and radials correspondingly >>> shorter than a 1/4 wavelength in order to take advantage of that >>> "off-center feed" aspect I mentioned in order to get a 50 ohm match. >>> >>> The only situation where resonant radials might be required is if you're >>> trying to decouple whatever is on the other side of the radials. In >>> that case, the radials act like a choke to keep current on the feedpoint >>> side of the resonant radials. You can see that effect with EZNEC as well. >>> >>> 73, >>> Dave AB7E >>> >> ______________________________________________________________ >> Elecraft mailing list >> Home:http://mailman.qth.net/mailman/listinfo/elecraft >> Help:http://mailman.qth.net/mmfaq.htm >> Post:mailto:[hidden email] >> >> This list hosted by:http://www.qsl.net >> Please help support this email list:http://www.qsl.net/donate.html >> Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Tony Estep
The only thing I would point out about the article is that it
basically is a tabulation of model results, an extension of the model presentation, what do you get if you run the model over and over kind of thing. The modeling of dirt is in itself an attempt to extend a limited paradigm of MF measurements (aka commercial broadcast band), focused on measurements at the ground for very practical reasons (Norton-Sommerfield) and has its own set of well-known issues. It is quite common to model radial kinds of issues and then install a design and find quite different results. Dirt, and all its variability, remains notoriously resistant to being modeled. Modeling can, I say "can", get one in the neighborhood and it's back to cut and measure, and a degree of common sense. 73, Guy. On Mon, Dec 20, 2010 at 10:14 PM, Tony Estep <[hidden email]> wrote: > For those who wish to pursue the radials question further, here's one of the > many publications on the subject. This one is replete with numerous tables > and graphical representations of the incremental value of more and longer > radials in various types of soil: > > http://www.ncjweb.com/k3lcmaxgainradials.pdf > > > > Tony KT0NY > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: Inverted-L (was OT: Vertical antenna)
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Logically .....
You may as well have a big loss in the near-field and get it over with. That way you'll have less to loose in the far field! Steve N4LQ ----- Original Message ----- From: "Guy Olinger K2AV" <[hidden email]> To: "Tony Estep" <[hidden email]> Cc: <[hidden email]> Sent: Tuesday, December 21, 2010 10:28 AM Subject: Re: [Elecraft] Inverted-L (was OT: Vertical antenna) > The only thing I would point out about the article is that it > basically is a tabulation of model results, an extension of the model > presentation, what do you get if you run the model over and over kind > of thing. The modeling of dirt is in itself an attempt to extend a > limited paradigm of MF measurements (aka commercial broadcast band), > focused on measurements at the ground for very practical reasons > (Norton-Sommerfield) and has its own set of well-known issues. It is > quite common to model radial kinds of issues and then install a design > and find quite different results. Dirt, and all its variability, > remains notoriously resistant to being modeled. Modeling can, I say > "can", get one in the neighborhood and it's back to cut and measure, > and a degree of common sense. > > 73, Guy. > > On Mon, Dec 20, 2010 at 10:14 PM, Tony Estep <[hidden email]> wrote: >> For those who wish to pursue the radials question further, here's one of >> the >> many publications on the subject. This one is replete with numerous >> tables >> and graphical representations of the incremental value of more and longer >> radials in various types of soil: >> >> http://www.ncjweb.com/k3lcmaxgainradials.pdf >> >> >> >> Tony KT0NY >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by David Gilbert
Actually, a DENSE radial solution in the near field DOES return
dividends, even over poor ground. The savings has to do with field cancellation at the ground, caused by uniform radials and the vertical radiator presenting equal and opposite fields to the dirt. This cancellation zone then "returns" the energy otherwise destined for worm-warming to the system to be added elsewhere, including proportionally to the sky wave. 73, Guy. On Tue, Dec 21, 2010 at 1:33 AM, David Gilbert <[hidden email]> wrote: > > > I suspect that Don was referring to the fact that poor ground > conductivity affected his low angle performance, and that is absolutely > true. There isn't a thing he or anyone else can do to change the far > field effects of poor ground. He can add lots of radials, buried or > otherwise, to improve feedpoint losses, but none of that has any effect > whatsoever on the far field pattern. > > 73, > Dave Ab7E > > > > On 12/20/2010 9:54 PM, Jan Erik Holm wrote: >> I hope people doesn´t learn from this statement. >> IMO this is as far from logic one can get. >> /Jim >> ------ >> On 2010-12-21 02:27, Don Wilhelm wrote: >>> The ground conductivity in my area is not the greatest, so I have >>> accepted the logical consequences of that fact. >>> >>> 73, >>> Don W3FPR >>> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Steve Ellington
We are developing a new class of non-radial 160m counterpoise
solutions. We had a few installed, and in use in the Stew Perry Topband Distance Challenge last weekend. (We're actually TESTING them before we go into blather mode, fancy that.) Look up W0UCE in the 3830 TBDC score listing and compare his score to others in his area (NC, VA, DC, PA). Nothing like contests to point out weaknesses, or none. As of last count, he was in the top quarter of single op high power scores, worldwide. W0UCE's transmit antenna had NO radials of any kind. He has a very minimal up 47 feet out 85 foot end-fed wire for 160 (limits dictated by available trees -- sound familiar?), working against a single wire elevated folded counterpoise, no radials. He has no space on his subdivision lot for beverages and used a pennant and K9AY loop for RX antennas. The counterpoise, while giving up on field cancellation loss below (the gift of DENSE radial fields) is designed to minimize ground induction losses underneath while being an effective counterpoise -- return energy for use in the RADIATING element. His words were "I felt loud." There ARE significant differences between actual measurements and model predictions (the expensive NEC4 pro EZNEC stuff) which we have not explained (not for lack of trying), but if you really want to test something, put it on line in a contest and go head to head with everyone else. There's no BS in contest results, just stark reality. You either beat or get beat (think NASCAR and tire and engine testing). W0UCE's signal over the period of the contest is documented in the Reverse Beacon Network, and we can compare it to anyone else's in the USA over the contest period. Jack's category of station is "small lot little guy, running an amp." Don, if you're interested, you're local, and we could put up one at your place, including the cook's tour about how we think it works. The 160m version of the counterpoise fits inside a a 45 degree right triangle that has short sides of 60 feet and a hypotenuse of 86 feet, to get the max out of small lots. It's specifically being designed for the little guy. UCE lives in Youngsville and a tour is easily arranged if you're interested. We won't be asking anyone to put up something we haven't already tried and tested. 73, Guy. On Tue, Dec 21, 2010 at 10:32 AM, Steve Ellington <[hidden email]> wrote: > Logically ..... > > You may as well have a big loss in the near-field and get it over with. > > That way you'll have less to loose in the far field! > > > Steve > N4LQ > ----- Original Message ----- > From: "Guy Olinger K2AV" <[hidden email]> > To: "Tony Estep" <[hidden email]> > Cc: <[hidden email]> > Sent: Tuesday, December 21, 2010 10:28 AM > Subject: Re: [Elecraft] Inverted-L (was OT: Vertical antenna) > > >> The only thing I would point out about the article is that it >> basically is a tabulation of model results, an extension of the model >> presentation, what do you get if you run the model over and over kind >> of thing. The modeling of dirt is in itself an attempt to extend a >> limited paradigm of MF measurements (aka commercial broadcast band), >> focused on measurements at the ground for very practical reasons >> (Norton-Sommerfield) and has its own set of well-known issues. It is >> quite common to model radial kinds of issues and then install a design >> and find quite different results. Dirt, and all its variability, >> remains notoriously resistant to being modeled. Modeling can, I say >> "can", get one in the neighborhood and it's back to cut and measure, >> and a degree of common sense. >> >> 73, Guy. >> >> On Mon, Dec 20, 2010 at 10:14 PM, Tony Estep <[hidden email]> wrote: >>> For those who wish to pursue the radials question further, here's one of >>> the >>> many publications on the subject. This one is replete with numerous >>> tables >>> and graphical representations of the incremental value of more and longer >>> radials in various types of soil: >>> >>> http://www.ncjweb.com/k3lcmaxgainradials.pdf >>> >>> >>> >>> Tony KT0NY >>> ______________________________________________________________ >>> Elecraft mailing list >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/mmfaq.htm >>> Post: mailto:[hidden email] >>> >>> This list hosted by: http://www.qsl.net >>> Please help support this email list: http://www.qsl.net/donate.html >>> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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Guy,
How about some more details on the counterpoise? I am using a 40' vertical top-loaded with two 44' wires (in other words, I'm feeding the feedline of my dipole as a vertical) on 160, my ground system is a bunch of elevated radials running around the eaves of my house and some in-ground wires, and I don't 'feel loud'. I would love to replace the mess with a better ground system. On 12/21/2010 8:36 AM, Guy Olinger K2AV wrote: > We are developing a new class of non-radial 160m counterpoise > solutions. We had a few installed, and in use in the Stew Perry > Topband Distance Challenge last weekend. (We're actually TESTING them > before we go into blather mode, fancy that.) Look up W0UCE in the > 3830 TBDC score listing and compare his score to others in his area > (NC, VA, DC, PA). Nothing like contests to point out weaknesses, or > none. As of last count, he was in the top quarter of single op high > power scores, worldwide. > > W0UCE's transmit antenna had NO radials of any kind. He has a very > minimal up 47 feet out 85 foot end-fed wire for 160 (limits dictated > by available trees -- sound familiar?), working against a single wire > elevated folded counterpoise, no radials. He has no space on his > subdivision lot for beverages and used a pennant and K9AY loop for RX > antennas. The counterpoise, while giving up on field cancellation > loss below (the gift of DENSE radial fields) is designed to minimize > ground induction losses underneath while being an effective > counterpoise -- return energy for use in the RADIATING element. His > words were "I felt loud." > > There ARE significant differences between actual measurements and > model predictions (the expensive NEC4 pro EZNEC stuff) which we have > not explained (not for lack of trying), but if you really want to test > something, put it on line in a contest and go head to head with > everyone else. There's no BS in contest results, just stark reality. > You either beat or get beat (think NASCAR and tire and engine > testing). > > W0UCE's signal over the period of the contest is documented in the > Reverse Beacon Network, and we can compare it to anyone else's in the > USA over the contest period. Jack's category of station is "small lot > little guy, running an amp." > > Don, if you're interested, you're local, and we could put up one at > your place, including the cook's tour about how we think it works. > The 160m version of the counterpoise fits inside a a 45 degree right > triangle that has short sides of 60 feet and a hypotenuse of 86 feet, > to get the max out of small lots. It's specifically being designed > for the little guy. UCE lives in Youngsville and a tour is easily > arranged if you're interested. > > We won't be asking anyone to put up something we haven't already tried > and tested. > > 73, Guy. > > On Tue, Dec 21, 2010 at 10:32 AM, Steve Ellington<[hidden email]> wrote: >> Logically ..... >> >> You may as well have a big loss in the near-field and get it over with. >> >> That way you'll have less to loose in the far field! >> >> >> Steve >> N4LQ >> ----- Original Message ----- >> From: "Guy Olinger K2AV"<[hidden email]> >> To: "Tony Estep"<[hidden email]> >> Cc:<[hidden email]> >> Sent: Tuesday, December 21, 2010 10:28 AM >> Subject: Re: [Elecraft] Inverted-L (was OT: Vertical antenna) >> >> >>> The only thing I would point out about the article is that it >>> basically is a tabulation of model results, an extension of the model >>> presentation, what do you get if you run the model over and over kind >>> of thing. The modeling of dirt is in itself an attempt to extend a >>> limited paradigm of MF measurements (aka commercial broadcast band), >>> focused on measurements at the ground for very practical reasons >>> (Norton-Sommerfield) and has its own set of well-known issues. It is >>> quite common to model radial kinds of issues and then install a design >>> and find quite different results. Dirt, and all its variability, >>> remains notoriously resistant to being modeled. Modeling can, I say >>> "can", get one in the neighborhood and it's back to cut and measure, >>> and a degree of common sense. >>> >>> 73, Guy. >>> >>> On Mon, Dec 20, 2010 at 10:14 PM, Tony Estep<[hidden email]> wrote: >>>> For those who wish to pursue the radials question further, here's one of >>>> the >>>> many publications on the subject. This one is replete with numerous >>>> tables >>>> and graphical representations of the incremental value of more and longer >>>> radials in various types of soil: >>>> >>>> http://www.ncjweb.com/k3lcmaxgainradials.pdf >>>> >>>> >>>> >>>> Tony KT0NY >>>> ______________________________________________________________ >>>> Elecraft mailing list >>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>>> Help: http://mailman.qth.net/mmfaq.htm >>>> Post: mailto:[hidden email] >>>> >>>> This list hosted by: http://www.qsl.net >>>> Please help support this email list: http://www.qsl.net/donate.html >>>> >>> ______________________________________________________________ >>> Elecraft mailing list >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/mmfaq.htm >>> Post: mailto:[hidden email] >>> >>> This list hosted by: http://www.qsl.net >>> Please help support this email list: http://www.qsl.net/donate.html >> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html -- Vic, K2VCO Fresno CA http://www.qsl.net/k2vco/ ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: Inverted-L (was OT: Vertical antenna)
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In reply to this post by ARDUJENSKI
Observational note on radials on the ground. My 43x130 foot
inverted-L requires more inductance in the summer for resonance. I see the change about a month after ground freeze-up (but that may vary with moisture content of the ground). Fall usually exhibits saturated ground due to the rainy season, whereas spring is typically dry after the thaw (May is our sunniest month). My 50-70 foot chicken wire radials are short for 500-KHz but do have a higher velocity factor (not measured). I do not have property for 930-foot radials! More metal under the inverted-L would be better but this is my practical limit. I have not spent much time looking at 160m and 80m tuning of the antenna, but will, eventually. The original design was for a 80m half-square but comparison with the inverted-L does not make it desirable enough for the complication in design. The antenna hears well (Buffalo, NY on 511-KHz from Alaska). I will begin my winter beacon transmissions later this week (WSPR on 501-KHz, 4.15w ERP). The use of a 120-foot radial (shield of my VHF Heliax cable) makes the inverted-L near to a tuned counterpoise on 80m with the elevated 130-foot top wire of the inverted-L (in fact the top is too long when you add the 43-foot vertical wire). I'm sure there will be some interesting impedances with this antenna as frequency is moved. Fortunately, the base coil can be adjusted using taps to find resonance. Impedance match is a separate issue. Before adding a base coil I could load the inverted-L on 80m using an antenna tuner at the radio. But this would have high SWR on the coax with additional loss. On 500-KHz I have Z = 53 +j0 on the coax by tapping above the grounded end of the base coil. 73, Ed - KL7UW, WD2XSH/45 ====================================== BP40IQ 500 KHz - 10-GHz www.kl7uw.com EME: 144-1.4kw*, 432-100w*, 1296-testing*, 3400-winter? DUBUS Magazine USA Rep [hidden email] ====================================== *temp not in service ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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