L.B.'s results indicate that my model is on the right track (the
loading losses are about 1dB) so I decided to re-run the test
over ground. I chose 75 feet again with no other antennas, guy
wires or any other reflection sources. Here are the numbers at
24 degrees elevation (peak of the main lobe):
Angle Gain F/B
(degrees) (dBi) (dB)
0 10.47 15.00
5 10.43 14.66
10 10.33 13.63
15 10.17 12.42
20 9.96 10.94
25 9.71 9.42
30 9.43 7.95
35 9.13 6.57
40 8.85 5.33
45 8.57 4.23
50 8.31 3.26
60 7.90 1.76
70 7.62 0.74
80 7.47 0.18
90 7.43 0.00
The driven element alone (a loaded rotatable dipole) shows a "gain"
of 7.43 dBi at and elevation angle of 24 degrees.
As with LB's results, the front to side degraded even more quickly
than F/B although F/S of the loaded two-element beam was not as good
as the full-size elements. As in free-space, gain does not fall off
very quickly until the rotation angle reaches about 30 degrees.
However, even 10 degrees of rotation has a significant effect on
pattern (F/B and F/S).
73,
... Joe Subich, W8IK/4 ex-AD8I
<W8IK@IBM.NET>
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