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#1
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"Quarter wave ground mounted radials are a waste of wire."
I just read the following on one of the mailing lists I subscribe to: "Quarter wave ground mounted radials are a waste of wire and a hold over from the olden days. Check the antenna handbook, the new philosophy is more and shorter. The thing is that the bulk of the energy from the vertical antenna is near the base of the antenna and this is what you are trying to capture. A quarter wave radial sounds logical but the planet will detune it so a quarter wave means nothing to the current." What say you all? |
#2
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"Quarter wave ground mounted radials are a waste of wire."
we all agree of course!
"Rick (W-A-one-R-K-T)" wrote in message news I just read the following on one of the mailing lists I subscribe to: "Quarter wave ground mounted radials are a waste of wire and a hold over from the olden days. Check the antenna handbook, the new philosophy is more and shorter. The thing is that the bulk of the energy from the vertical antenna is near the base of the antenna and this is what you are trying to capture. A quarter wave radial sounds logical but the planet will detune it so a quarter wave means nothing to the current." What say you all? |
#3
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"Quarter wave ground mounted radials are a waste of wire."
Rick (W-A-one-R-K-T) wrote:
"Quarter wave ground mounted radials are a waste of wire and a hold over from the olden days. Check the antenna handbook, the new philosophy is more and shorter. The thing is that the bulk of the energy from the vertical antenna is near the base of the antenna and this is what you are trying to capture. A quarter wave radial sounds logical but the planet will detune it so a quarter wave means nothing to the current." What say you all? The ground does detune ground mounted radials because the fields are attenuated by the ground. Twice as many 1/8WL buried radials may work as well or better than half as many 1/4WL buried radials. -- 73, Cecil http://www.w5dxp.com |
#4
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"Quarter wave ground mounted radials are a waste of wire."
On Sun, 23 Sep 2007 12:46:30 -0400, "Rick (W-A-one-R-K-T)"
wrote: What say you all? Hi Rick, Sounds like the ghost of Reggie. So, in honor to his aphorisms and homilies, it should be noted that adding more wire to that which is conducting nearly nothing - is a waste of wire. If we are to reduce this to sound-bites, then the taller the radiator, the longer the radial(s). If I recall Reggie's other homilies correctly, there should be a one-to-one correlation (length=height). As far as efficiency goes, the difference between 20 radials and 120 is hardly noticeable on the S-Meter. Real engineers can measure differences, but they are far and few between (and don't QSO). 73's Richard Clark, KB7QHC |
#5
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"Quarter wave ground mounted radials are a waste of wire."
"Rick wrote
... What say you all? Read "Ground Systems as a Factor in Antenna Efficiency" by Brown, Lewis & Epstein of RCA Labs, published in the June, 1937 issue of The Proceedings of the I.R.E. It proves otherwise. RF |
#6
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"Quarter wave ground mounted radials are a waste of wire."
On Sun, 23 Sep 2007 12:59:49 -0500, Richard Fry wrote:
"Rick wrote ... What say you all? Read "Ground Systems as a Factor in Antenna Efficiency" by Brown, Lewis & Epstein of RCA Labs, published in the June, 1937 issue of The Proceedings of the I.R.E. It proves otherwise. Honest question, does it matter whether the objective is a strong ground wave as in AM broadcast or skywave as in amateur operation? I am installing a Hustler 4BTV this fall and have put down (so far) 16 radials that range from about 18 to 35 feet in length due to my servere space restrictions. I may add 16 more later this fall as an experiment. 73, de Nate -- "The optimist proclaims that we live in the best of all possible worlds, the pessimist fears this is true." |
#7
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"Quarter wave ground mounted radials are a waste of wire."
On Sep 25, 4:53 pm, Nate Bargmann
wrote: On Sun, 23 Sep 2007 12:59:49 -0500, Richard Fry wrote: "Rick wrote ... What say you all? Read "Ground Systems as a Factor in Antenna Efficiency" by Brown, Lewis & Epstein of RCA Labs, published in the June, 1937 issue of The Proceedings of the I.R.E. It proves otherwise. Honest question, does it matter whether the objective is a strong ground wave as in AM broadcast or skywave as in amateur operation? No, the local ground losses effect the efficiency the same no matter what skip type, angles used , etc.. It will be equally weaker in all directions and angles if you add more ground loss. The pattern will still be the same in all directions, as all angles suffer equally. Same pattern, just less field strength if you add more ground loss. MK |
#8
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"Quarter wave ground mounted radials are a waste of wire."
"Nate Bargmann" wrote
Honest question, does it matter whether the objective is a strong ground wave as in AM broadcast or skywave as in amateur operation? ______ Hi, Nate - The skywave is important not only to amateur operators, but even more so to the nighttime coverage of stations designated by the FCC as Class A AM broadcast stations (the former "clear channel" stations). However a poor r-f ground system for a vertical monopole radiator will reduce the radiated field at ALL elevation angles including those producing a useful skywave-- not just in the horizontal plane producing the ground wave. RF http://rfry.org |
#9
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"Quarter wave ground mounted radials are a waste of wire."
"Nate Bargmann" wrote in message news On Sun, 23 Sep 2007 12:59:49 -0500, Richard Fry wrote: "Rick wrote ... What say you all? Read "Ground Systems as a Factor in Antenna Efficiency" by Brown, Lewis & Epstein of RCA Labs, published in the June, 1937 issue of The Proceedings of the I.R.E. It proves otherwise. Honest question, does it matter whether the objective is a strong ground wave as in AM broadcast or skywave as in amateur operation? I am installing a Hustler 4BTV this fall and have put down (so far) 16 radials that range from about 18 to 35 feet in length due to my servere space restrictions. I may add 16 more later this fall as an experiment. 73, de Nate It would be interesting to follow the change in VSWR as you add individual radials. Some years ago, there was a discussion of adding radials until the VSWR stopped increasing. This was based on an expected feedpoint resistance of 36 ohms, and an assumption that the ground losses were 15 ohms or less. So at the worst case, the VSWR was near 1:1. The best case, with a ground loss approaching 0 ohms, would have a VSWR of 50/36= 1.39:1. I want to attribute the original discussion to W2DU, but I stop short of that, in case I don't remember correctly. |
#10
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"Quarter wave ground mounted radials are a waste of wire."
On Wed, 26 Sep 2007 16:56:27 GMT, "Wayne"
wrote: It would be interesting to follow the change in VSWR as you add individual radials. Some years ago, there was a discussion of adding radials until the VSWR stopped increasing. This was based on an expected feedpoint resistance of 36 ohms, and an assumption that the ground losses were 15 ohms or less. So at the worst case, the VSWR was near 1:1. The best case, with a ground loss approaching 0 ohms, would have a VSWR of 50/36= 1.39:1. Hi Wayne, This strategy may also have you stop adding radials too early when your antenna presented 36 Ohms looking into a ground loss of 33 Ohms (same SWR of 1.39). 73's Richard Clark, KB7QHC |
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