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Re: [TowerTalk] 40m 4el KLM - replacing linear loading with coils

To: towertalk@contesting.com
Subject: Re: [TowerTalk] 40m 4el KLM - replacing linear loading with coils
From: jimlux <jimlux@earthlink.net>
Date: Tue, 28 Apr 2020 20:35:09 -0700
List-post: <mailto:towertalk@contesting.com>
On 4/28/20 7:08 PM, Michael Tope wrote:
Yeah, I was expecting the two-coil design to have better VSWR bandwidth. Did you compare the radiation resistance of the two designs? I would expect the one coil design to have a lower radiation resistance.
Perhaps the lack of difference in the VSWR bandwidth of the two designs 
explains why the Cushcraft 402CD/XM240 designs go to the trouble of 
using capacitance hats after the loading coils.
capacitance hats make the current distribution more uniform along the 
element - that helps with gain as Dave just pointed out.
A sort of ultimate version is a tesla coil - uniformly loaded, with big 
capacitance on each end, with the "element" being a tiny fraction of a 
wavelength.  It's a parallel LC circuit.
Of course, a TC is a terrible radiator.



73, Mike W4EF..............

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