Here's a really inexpensive beam antenna for 40m. It's based
on an idea from Jesse, W6KKT. It essentially takes the power
from one side of a vertical and focuses it toward the other
side for a 3dB gain. I appologize if anybody has invented
this or tried it before. It has a very low take-off-angle
without a man-made ground plane. It has a top-hat and
counterpoise per element.
+-------- +---------
| 21ft | 21.5ft
26ft | |
| |
<== | |
| |
F-------- +---------
The arrow shows the direction of beaming. The signal is
vertically polarized. The feedpoint is at "F" and is a
pretty good match for either 50 ohm or 75 ohm coax. A 1:1
choke/balun is needed to balance the currents. The feedpoint
is 11 ft. off the ground. The top of the antenna is at 37
ft. The horizontal sections on the left are 21 ft. and the
horizontal sections on the right are 21.5 ft. The antenna
has a gain of about 3dBi with a TOA of 22 deg at the highest
gain point.
I'm going to build one of these and will report how close
EZNEC came to predicting dimensions and impedance. This
antenna and others are described in detail on my web page:
http://people.delphi.com/CecilMoore
73, Cecil, W6RCA, OOTC
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