Topband: FCP Question

[CUTTER DAVID]

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" <richard at karlquist.com> 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
> _________________
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