Hi Rob
I see copper prices have doubled in the last year.
My intention is to compare and contrast the cost and performance of short
verticals over a large field of ground radials v the very modest amount of wire
required for the FCP. In Guy's article
https://k2av.com/Olinger_NCJ_article_on_FCP.pdf
he says "The reason for the FCP is twofold: minimal space and a low-loss
alternative to radials." I would add that it is also lower cost, to your
point.
I interpret his analysis as saying that the layout of the FCP minimises its own
ground loss so well that only the radiator's ground loss is left to compare to
the "gold standard" of 120 ground radials.
I hope someone will jump in and correct me if I've misinterpreted that. If
not, would it be correct to say that the FCP method of loss reduction differs
only by 1.7 dB (from Guy's article) compared to the "gold standard" of 120
ground radials?
I don't have that Griffith book, so, would you summarise the difference between
120 ground radials and the fewer radials proposed when using <1/4 w vertical?
I'd like to get a feel for how it compares to the FCP method.
73 David G3UNA
> On 08 January 2022 at 18:14 Rob Atkinson <ranchorobbo@gmail.com> wrote:
>
>
> I can't comment on the folded counterpoise because I am not familiar
> with it. The "broadcast model" which I take to mean 120 radials is
> used because in the case of a 90 degree tower on medium wave, the
> earth current intensity is far enough from the feed point to
> necessitate a higher number of radials so that as they diverge, they
> are not so far apart from each other that the earth losses are
> unacceptable. Few hams have 1/4 w. towers for 160 m., and instead
> employ shorter vertical radiators such as inverted Ls* and Ts, (1/8 w.
> for example) so the ground current intensity is high much closer to
> the feedpoint. This means that fewer radials can be used because they
> are shorter and at their ends, are still an acceptable separation from
> each other. Of course, ground conductivity plays a part also. This
> is good news for hams who want to save money on expensive wire. All
> of this is detailed in the Griffith book I referenced previously.
>
> 73
> Rob
> K5UJ
>
> *Unlike the T, the horizontal portion of the inverted L radiates.
> W1BB recommended extending radials that run along underneath it if
> possible, and I think that was good advice.
>
> On Sat, Jan 8, 2022 at 9:27 AM CUTTER DAVID <d.cutter@ntlworld.com> wrote:
> >
> > Rob
> >
> > I recall a discussion on here some years ago which proposed that, whilst
> > being an amazing antenna for top band, if you could achieve it, the
> > broadcast model was not necessarily the best use of resources for amateur
> > purposes, on the basis that broadcasters are mainly interested in ground
> > wave to cover a defined relatively short range service area, whereas
> > amateurs a more interested in dx.
> >
> > I don't recall how that discussion ended, but for purposes of saving wire,
> > at least, the K2AV folded counterpoise (FCP) must be about as good as
> > anyone could attain. How it performs against that broadcast model would be
> > of interest.
> >
> > David G3UNA
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