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Re: Topband: Skimmer calibration

To: "topband" <topband@contesting.com>
Subject: Re: Topband: Skimmer calibration
From: "Tom W8JI" <w8ji@w8ji.com>
Reply-to: Tom W8JI <w8ji@w8ji.com>
Date: Wed, 20 Aug 2014 12:05:58 -0400
List-post: <topband@contesting.com">mailto:topband@contesting.com>
I said:

That just isn't factual at all. Radials under the vertical antenna have virtually no effect on wave angle unless they are sparse and grossly unbalanced, allowing them to radiate like a low horizontal antenna.

Radials change the efficiency, not the pattern, unless the radials radiate like a dipole.

73 Tom


Note that I didnt say anything about changing the pattern, just the energy included at low angles and where the efficiency starts at the base and at the often poorly understood Fresnel Zone if you really want more power in those low angles and not heating worms or sand granules.

That, by definition, is a pattern change.

You said it improves groundwave. What you think happen just does not happen.

It improves efficiency. It does not change elevation pattern, it does not change Fresnel zone losses significantly. It does not improve groundwave any significant amount more than it changes sky wave.

This is because the "often poorly understood" Fresnel zone extends far beyond practical radial field area, and virtually all of the ground wave attenuation from soil losses is miles from the antenna over the entire long length of a path. It is not localized loss.

73 Tom


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