In article , John S
wrote:

On 5/25/2013 1:48 AM, David Ryeburn wrote:

.... (snip)

Many thanks. That confirms what I thought, except that I had expected
the antenna to be on the capacitive side of resonance on 30 metres. All
the figures indicate that my 142.7 ft loop is just a bit too long.

Well, I didn't know your wanted to see the results with a 142.7 ft loop.

I thought that that would be about the resonant length for a 7.05 MHz
full-wave closed loop (1005/7.05 = 142.55). What length were you using,
for your revised figures that took into account the presence of the
ground?

I thought you wanted to start with it resonant at 7.05MHz and let the
other figures fall where they may. Here it is repeated for 142.7ft.

3.525MHz 12.41 + J 59.12 ohms open
7.05MHz 116.3 - J 83.72 ohms closed
10.125MHz 244.3 - J 82.4 ohms open
14.05MHz 212.9 - J 78.4 ohms closed
21.15MHz 112 + J 33.87 ohms closed
28.05MHz 258 + J 77.07 ohms closed

Thank you for the re-computation. These figures do make 15 and 10 better
than they were (but maybe not good enough, considering the added loss in
RG-174 at those higher frequencies). I also haven't thought about the
other two WARC bands, and I'm not particularly interested in 60 metres
where you can't QSY except in discrete steps. (And I don't think Canada
has fully implemented 60 metres for hams as yet.)


In article ,
Jeff Liebermann wrote:

On Fri, 24 May 2013 23:48:41 -0700, David Ryeburn
wrote:

Does anyone know of
antenna modelling software for the Mac?

http://www.w7ay.net/site/Applications/cocoaNEC/


I'll look into this one. Have you used cocoaNEC?

David, VE7EZM

--
David Ryeburn

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