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Re: Topband: Short radials?

To: <topband@contesting.com>
Subject: Re: Topband: Short radials?
From: "Tom W8JI" <w8ji@w8ji.com>
Reply-to: Tom W8JI <w8ji@w8ji.com>
Date: Thu, 27 Sep 2012 15:25:25 -0400
List-post: <topband@contesting.com">mailto:topband@contesting.com>
It's important to note that this data is for AM broadcast towers, which in the time frame when this work was done, were mostly a quarter wave tall to 5/8 wave tall. >

We should look at the data and not assume. The original paper is called "Ground Systems as a factor in Antenna System Efficiency" and based on a study for RCA corporation. It includes measurements of screened and unscreened systems, and concluded screens offer no additional advantage.

I'm pretty sure I have the original papers around here in a box someplace. The B L and E data is for various heights from very short heights up to 90 degrees tall, with a variety of ground systems.

Very few AM BC towers are 5/8th wave. Many are shorter than 1/4 wave, and most are actually someplace around 1/4 wave tall.

Richard suggested one of the best sources for conventional radial system information on radiators less than 90 degrees tall. The graphs he posted are for radiators from a few degrees to 90 degrees tall.

On 9/27/2012 10:14 AM, Richard Fry wrote:
The measured data linked below shows how the number of buried radials affects the performance of monopoles of various height to 90 degrees, for an applied power of 1 kW. Earth conductivity at the test site was about 4 mS/m.

http://i62.photobucket.com/albums/h85/rfry-100/BLandERadials.gif
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UR RST IS ... ... ..9 QSB QSB - hw? BK


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UR RST IS ... ... ..9 QSB QSB - hw? BK

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