Re: Topband: FCP Question
On 1/8/2021 10:41 AM, Guy Olinger K2AV wrote: Hi Rick, There is no problem modeling an FCP. You do have to do the parallel wires a certain way that’s documented in EZNEC since 1997 (version 2). What do you perceive to be the issue? 73, Guy K2AV On Fri, Jan 8, 2021 at 11:10 AM Richard (Rick) Karlquist I am vaguely aware that for a 2 wire line, EZNEC recommends that you replace it with the EZNEC transmission line element. It also says that EZNEC will not model the effect of the line in common mode, AFAIK. In any event, the FCP consists of 3 parallel wires. I have no idea what to do with such a structure. So perhaps there is no problem modeling an FCP; it's just that I haven't got a clue. I would be happy to learn how to do it. Could you explain what to do or post an EZNEC file? 73 Rick N6RK _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: FCP Question
Hi Rick, There is no problem modeling an FCP. You do have to do the parallel wires a certain way that’s documented in EZNEC since 1997 (version 2). What do you perceive to be the issue? 73, Guy K2AV On Fri, Jan 8, 2021 at 11:10 AM Richard (Rick) Karlquist < rich...@karlquist.com> wrote: > It would be interesting to compare an FCP to > N6BT's single spiral counterpoise. It models > well on EZNEC. The FCP, unfortunately, cannot > be modeled with NEC, AFAIK. > > Rick N6RK > > On 1/7/2021 9:35 PM, WI6X wrote: > > Ted, > > Read through Jim K9YC’s "Power Point slides for a presentation about > 160M antennas at Pacificon in October 2012. Getting On 160M From a Small > Lot (and Larger Ones Too). October 2012” > > http://k9yc.com/160MPacificon.pdf > > K2AV Folded Counterpoise information begins on page 68 of the PDF. > > 73, > > Jim WI6X > > > >> On Jan 4, 2021, at 9:47 AM, Salvatore [Ted] K2QMF > wrote: > >> > >> Hello Topbanders, > >> > >> I have an inverted "L" with 4 elevated radials! > >> I seem to have too much ground losses! > >> I am wondering if I can add an 160 FCP to help with the ground losses?? > >> Any info would be much appreciated! > >> Thanks and 73, > >> Ted K2QMF > >> _ > >> Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > > > > _ > > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > > > _ > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > -- Sent via Gmail Mobile on my iPhone _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: FCP Question
I discussed the antenna with him at Visalia and I picked up a leaflet. He told me that he wanted to patent it but I pointed out that it was in the Moxon book HF Antennas For All Locations 1982, ie public knowledge. I have built several like it just for fun and they work. It's basically an off centre fed antenna. See the book page 155 for various systems like it. No magic. David G3UNA > On 08 January 2021 at 17:35 "Richard (Rick) Karlquist" > wrote: > > > On 1/8/2021 8:33 AM, Salvatore ["Ted"] K2QMF wrote: > > Hello Rick, > > Can you point me to the info on N6BT's spiral counterpoise?? > > Many Thanks and 73, > > Ted K2QMF > > > > I'm also posting this reply to the reflector in case others > are interested. > > I couldn't find anything N6BT published on this topic. > I think I learned about it from him at his Visalia booth. > > I was able to find this: > > https://circuitsalad.com/2015/09/13/vertical-with-tuned-spiral-counterpoise-updates/ > > The executive summary is: > > Assume the feedline terminates in a common mode > choke at the feedpoint. One output from the > choke connects to the vertical driven element. > The other output is connected to a wire that is > say, 115 feet long. It goes out from the antenna > 17.7 feet, and then is formed into a square 25 feet > on a side. The far end of the wire is NOT electrically > connected to anything, but is mechanically supported > with a string, etc. The corners of the square lie on a > circle with a radius of 17.7 ft, and the vertical > is at the center. The feedpoint, choke and spiral > radial are elevated by 5 to 20 feet above ground. > The idea is that the 115 ft wire is resonant after > taking into account the reduced VF due to ground. > You could try to adjust the wire to resonance by > measuring its impedance at the antenna end against > a ground rod using a VNA, and adjust the length. > So the whole thing fits into a 25x25 foot square. > That should work even on a postage stamp lot. > Anyway, it does look reasonable on EZNEC. > > 73 > Rick N6RK > _ > Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: FCP Question
On 1/8/2021 8:33 AM, Salvatore ["Ted"] K2QMF wrote: Hello Rick, Can you point me to the info on N6BT's spiral counterpoise?? Many Thanks and 73, Ted K2QMF I'm also posting this reply to the reflector in case others are interested. I couldn't find anything N6BT published on this topic. I think I learned about it from him at his Visalia booth. I was able to find this: https://circuitsalad.com/2015/09/13/vertical-with-tuned-spiral-counterpoise-updates/ The executive summary is: Assume the feedline terminates in a common mode choke at the feedpoint. One output from the choke connects to the vertical driven element. The other output is connected to a wire that is say, 115 feet long. It goes out from the antenna 17.7 feet, and then is formed into a square 25 feet on a side. The far end of the wire is NOT electrically connected to anything, but is mechanically supported with a string, etc. The corners of the square lie on a circle with a radius of 17.7 ft, and the vertical is at the center. The feedpoint, choke and spiral radial are elevated by 5 to 20 feet above ground. The idea is that the 115 ft wire is resonant after taking into account the reduced VF due to ground. You could try to adjust the wire to resonance by measuring its impedance at the antenna end against a ground rod using a VNA, and adjust the length. So the whole thing fits into a 25x25 foot square. That should work even on a postage stamp lot. Anyway, it does look reasonable on EZNEC. 73 Rick N6RK _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: FCP Question
It would be interesting to compare an FCP to N6BT's single spiral counterpoise. It models well on EZNEC. The FCP, unfortunately, cannot be modeled with NEC, AFAIK. Rick N6RK On 1/7/2021 9:35 PM, WI6X wrote: Ted, Read through Jim K9YC’s "Power Point slides for a presentation about 160M antennas at Pacificon in October 2012. Getting On 160M From a Small Lot (and Larger Ones Too). October 2012” http://k9yc.com/160MPacificon.pdf K2AV Folded Counterpoise information begins on page 68 of the PDF. 73, Jim WI6X On Jan 4, 2021, at 9:47 AM, Salvatore [Ted] K2QMF wrote: Hello Topbanders, I have an inverted "L" with 4 elevated radials! I seem to have too much ground losses! I am wondering if I can add an 160 FCP to help with the ground losses?? Any info would be much appreciated! Thanks and 73, Ted K2QMF _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
