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#1
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![]() wrote in message ... In rec.radio.amateur.antenna gareth wrote: Spike recently commented upon his success with DX by implementing at the base of his vertical antenna a fan of 300 ground wires pointing in the direction that he wished to work. I've not seen my suggestion before, but why could one not just have a 1/4 wave vertical, with the other 1/4 wave making up the dipole being rotatable for the desired direction of working? Out of curiousity, I modeled the following: freq: 14.2 MHz radial height: 3 inches Material: #12 copper ground: average I optimized the radiator and radial lengths for minimum reactance and got: radiator: 196 inches radial: 190.6 inches R: 75 Ohms X: -0.4 Ohms SWR: 1.5 Maximum gain: -1.8 dBi in the direction of the radial and an elevation angle of 30 degrees Reverse gain: -6.8 dBi Polarization: primarily vertical with horizontal lobes 90 degrees to the radial a -15 dB down from the max vertical gain. Cool. Any idea what the numbers would be for the 300 radial configuration? |
#2
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In rec.radio.amateur.antenna Wayne wrote:
wrote in message ... In rec.radio.amateur.antenna gareth wrote: Spike recently commented upon his success with DX by implementing at the base of his vertical antenna a fan of 300 ground wires pointing in the direction that he wished to work. I've not seen my suggestion before, but why could one not just have a 1/4 wave vertical, with the other 1/4 wave making up the dipole being rotatable for the desired direction of working? Out of curiousity, I modeled the following: freq: 14.2 MHz radial height: 3 inches Material: #12 copper ground: average I optimized the radiator and radial lengths for minimum reactance and got: radiator: 196 inches radial: 190.6 inches R: 75 Ohms X: -0.4 Ohms SWR: 1.5 Maximum gain: -1.8 dBi in the direction of the radial and an elevation angle of 30 degrees Reverse gain: -6.8 dBi Polarization: primarily vertical with horizontal lobes 90 degrees to the radial a -15 dB down from the max vertical gain. Cool. Any idea what the numbers would be for the 300 radial configuration? Likely not a lot of difference. I could add a few, but not going to spend the time to add 300. -- Jim Pennino |
#3
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#4
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#5
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#6
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#8
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John S wrote:
On 11/30/2015 11:35 AM, Spike wrote: On 29/11/2015 23:24, wrote: OK, I added radials for a total of 5 in a 45 degree spread and optimized for minimum reactance. radiator: 203 inches, radial: 186 inches, R: 52.4 Ohms, X: 0.4 Ohms SWR: 1.1, Maximum gain: -.18 dBi in the direction of the radial and an elevation angle of 30 degrees, Reverse gain: -3.7 dBi Note with one radial the F/B ratio is about 5 dB and with five radials it is about 3dB. About the only thing I can see worth noting about this antenna is that it shows more radials are better, but everyone already knows that. Imagine a case whereby someone digs up the soil around the base of a vertical antenna, a couple of feet deep and as far out as the antenna is tall. Into this they mix 2 percent of high-aspect-ratio thin conducting fibres, say about a foot long, and then replace the soil. 2 percent of conducting fibres in an essentially non-conducting medium is about the minimum proportion necessary to reach the percolation threshold.. What results from your modelling exercise do you get in this case? Are you unable to model this yourself or are you just trolling? Spike's a long time and well known troll, yes. -- STC // M0TEY // twitter.com/ukradioamateur |
#9
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In rec.radio.amateur.antenna Spike wrote:
On 29/11/2015 23:24, wrote: OK, I added radials for a total of 5 in a 45 degree spread and optimized for minimum reactance. radiator: 203 inches, radial: 186 inches, R: 52.4 Ohms, X: 0.4 Ohms SWR: 1.1, Maximum gain: -.18 dBi in the direction of the radial and an elevation angle of 30 degrees, Reverse gain: -3.7 dBi Note with one radial the F/B ratio is about 5 dB and with five radials it is about 3dB. About the only thing I can see worth noting about this antenna is that it shows more radials are better, but everyone already knows that. Imagine a case whereby someone digs up the soil around the base of a vertical antenna, a couple of feet deep and as far out as the antenna is tall. Into this they mix 2 percent of high-aspect-ratio thin conducting fibres, say about a foot long, and then replace the soil. 2 percent of conducting fibres in an essentially non-conducting medium is about the minimum proportion necessary to reach the percolation threshold.. What results from your modelling exercise do you get in this case? Modeling thing buried in the soil requires professional software that costs on the order of $1,000. To do this with reasonably priced (for a hobby) software requires that effective soil conductivity be determined. Send me either $1,000.00 or the effective soil conductivity and I'll be glad to do it. -- Jim Pennino |
#10
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