I want to thank everyone who responded on and off list to my request for
suggestions about what to put on a rooftop 10 stories up!
I have been EZNEC-ing my butt off all day, and so far the winner is the
suggestion of KL7UW and W4TV, a 20'x30' horizontal rectangular loop
about 20' above the roof, fed with 600-ohm open wire line in the center
of one of the longer sides.
This antenna will have excellent horizontal and vertical patterns on all
bands 80 through 10 meters, and should be easily tunable on 40-10 (for
80 I may need to do something special to match it).
The old standby, a tuned 44' doublet works fine for 40 and 20, but the
pattern breaks up and produces much too much cloud-warming on higher
bands. Remember, the antenna will be at 120' above ground. The
horizontal pattern is also not ideal on all bands.
I got a lot of votes for a vertical, which is the easiest solution. But
the horizontal antennas will be quieter in the urban environment. They
have some gain in the desired direction. Also I have had better luck
from the standpoint of RFI with balanced horizontal antennas.
Now there is just the mechanical question of how to keep the poles that
hold up the loop at the corners of the roof from bowing inward too much.
There's nothing to guy them to.
I also appreciate the forbearance of Eric S., who tolerated this OT
discussion for so long. FWIW, RF going into the antenna will come from
my K2 and K3.
--
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/
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