With a few minutes of unscheduled time and a need for a bit of intellectual
stimulation that could not be provided by the sophomoric responses to the
troll's messages on the news group, I decided to investigate the antenna put
forth by one or more of our Greek attendees. Unfortunately, the original
drawing of the antenna seems to have been withdrawn.

I assumed: a "small" angle of 60 degrees, #12 AWG Cu wire, and each of
the seven wires to be 21 meters long cut into 21 segments.

The resulting antenna has a FS fundamental resonance at about 7.45 MHz
with a 1.5:1 SWR bandwidth relative to 900 ohms of about 500 kHz. The next
higher resonance occurs at about 11.27 MHz with a 1.5:1 SWR bandwidth of
about 150 kHz relative to 200 ohms.

The antenna was elevated 40 meters above perfect ground and evaluated
at 7.45 MHz. For most elevation angles, the pattern has four lobes. The
two front lobes have a minor dip between them over elevation angles from
something like 10 degrees to something like 25 degrees. Below an elevation
angle of something like 10 degrees, the mid-lobe null is pronounced. Side
nulls are excellent. Front-to-back ratio is poor.

If one wished to cover a fairly large sector at 1 Mm or so and needed a
straight-on null of a distant station, this might be a useful antenna.

I did not consider the effects of rotating the antenna 90 degrees so
that the antenna is in the X-Y plane.

Here are the FS coordinates that I used for the ends of the wires:
(X,Y,Z)
0, -10.5,0
0, 10.5,0
0, -7.687, 10.5
0, -28.687, 10.5
0, -28.687, -10.5
0, -7.687, -10.5

The wire from 0,-10.5,0 to 0, 10.5,0 was driven at its mid-point.

73 Mac N8TT
--
J. Mc Laughlin; Michigan U.S.A.
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