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Re: LF: LF-antenna with top load

To: [email protected]
Subject: Re: LF: LF-antenna with top load
From: "Mike Dennison" <[email protected]>
Date: Fri, 17 Sep 1999 14:04:31 +0100
In-reply-to: <[email protected]>
Organization: Radio Society of Great Britain
Reply-to: [email protected]
Sender: <[email protected]>
PA0SE wrote:
Refering to the last part of my second report (16.9.99 14.17) it is clear
that top loads are hardly a substitute for height. Even raising the
antenna from 10 to 15 m increases radiation resistance more than even the
largest top load can do. This is easily understood as radiation resistance
is proportional to height squared whereas the most a top load can do is
doubling the radiation resistance.

Ah, but that's EFFECTIVE height squared, and one effect of the top
load is to increase effective height by anything from 50% of actual
height (no top load) to 100% (quarter-wave top load). Are you really
saying that a 15m vertical will outperform a 10m inverted-L with a
1000m top load?

Why does a top load only double the radiation resistance? Isn't it a
function of total length, whether vertical or horizontal?

Mike, G3XDV (IO91VT)

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