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[TowerTalk] optimum vertical height

To: Towertalk Reflector <towertalk@contesting.com>
Subject: [TowerTalk] optimum vertical height
From: jimlux <jimlux@earthlink.net>
Date: Sun, 31 May 2009 16:25:20 -0700
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Or length, really...

Say you have a vertical that can be any arbitrary length, and you have a 
   (presumed perfect lossless) tuner at the base of the vertical. What 
length should one choose, if you want to operate all HF ham bands?

Obviously, there's lots of folks selling 43 foot verticals these days, 
but I suspect that's a length chosen to make sure the impedance isn't 
"bad" in the ham bands, when fed with a simple matching network (4:1 
transfomer, often with some leakage C) and coax to a tuner in the shack.

Is there a point of diminishing returns in height (e.g. the difference 
in performance on, say, 160m, is going to be tiny between 20 ft and 
25ft.. it's a "very short" radiator on both).

What about higher band performance (a very long radiator is going to be 
much longer than a 1/4 wavelength, so the pattern will start to have 
many vertical lobes, which may or may not have a big practical effect).

(The assumption of lossless tuner isn't all that unreasonable, at least 
for comparing the radiation performance..)

Jim


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