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[TowerTalk] trees and verticals

To: "" <>
Subject: [TowerTalk] trees and verticals
From: Roger Parsons <>
Reply-to: Roger Parsons <>
Date: Wed, 28 Dec 2011 09:26:26 -0800 (PST)
List-post: <">>
Jim Lux wrote:

"You're describing the difference between the near field (wooden element 
in Yagi) and far field (propagating through a box)."

Not really. The box could be in the near field or the far field (I know
it would then be quite a big box:-), and it would still attenuate the
signal received from the antenna at a distant point. The amount by which
it would attenuate it would depend on factors such as size, material,
thickness, frequency and so on.

An element in a parasitic array can be at any distance, although its affect
will be much greater with close spacings. (Witness the cases of pattern
distortion to some AM broadcast arrays caused by distant power line towers, 
steel-framed buildings, etc.)

The ultimate 'lossy element' is one that is totally non-conductive. It can
accept no power, so it can cause no losses.....

73 Roger

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