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[email protected] · April 4th 14, 06:26 PM posted to rec.radio.amateur.antenna

Wimpie wrote:
El 03-04-14 23:29, escribió:
On Thursday, April 3, 2014 2:28:40 PM UTC-5, Wimpie wrote:

Again, in free space the maximum is ALWAYS at zero elevation.

Except for the 5/8 lambda, as I mentioned.

That's only because you used 1/4 WL radials, which is a very
perverted design. Try it with 3/4 WL radials. That will give you
close to your textbook gain.

For zero elevation (relevant for line of sight comms in VHF and up),
the gain will virtually not improve when using horizontal 3/4 WL
radials. The horizontal radials don't contribute to the vertically
polarized wave.

And for an even better pattern use sloping 5/8 WL radials, which
will start approaching the gain of a dual 5/8 WL collinear.

A 5/8 system mounted at 13 feet (top of an average house) will have a
squarish pattern with a maximum of 4.4 dBi and a minimum of 2.2 dBi.

A 1/4 system at the same height has a circular pattern of 4.9 dBi.

In both cases the major elevation lobe is at 20 degrees.

Free space patterns can look wonderfull, but unless you live on the ISS
your antenna is going to be mounted over ground.

--
Jim Pennino