On Tue, 11 Sep 2007 09:51:30 -0700 (PDT), steve d wrote:
>How many radials should I put out?
The following is very good for the classic case of quarter wave
radials.
http://www.antennasbyn6lf.com/files/160_m_vertical_measurements.pdf
The author, N6LF, wrote the excellent material in recent editions of
the ARRL Antenna Book on the same topic, expanding it to cover
different lengths of radials. One conclusion of the Antenna Book
material is that a lot of shorter radials (1/8 wave, for example) is
better than a few longer ones (quarter wave). That's because the
loss is I squared R, and I is greatest closest to the base of the
antenna.
The compromise I settled on is 1/8 wave on 160. I started with about
20, added 10 or so, then added another 10. More is better, but you
hit the point of diminishing returns once you hit 30-40. That is,
going from four to 30 is typically good for a couple of dB, while
going from 30 to 60 is probably good for another half dB or so. It
is also true that radials make a greater difference over lousy soil
than over good soil.
Jim K9YC
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