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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