On Wed, 04 Sep 1996 10:09:37 -0600 Tony Wanschura <tonyjw@primenet.com>
writes:
>I'd like to ad 160m capability on a small city lot (120x50) with a 60
>foot tower. No room for radials of any kind, and I don't want to feed
>the tower anyway.
>
>I'm thinking of a 1/4 wave sloper incorporating linear loading, using
>a
>loading wire parallel to the radiating element. Has anyone done this,
>and what dimensions did you end up with?
>
>Tony
>KM0O
>
Hi Tony,
Here's a description of my 160 half sloper on a 70x120 city lot.
The tower is 48 feet high, with a KT-34XA at 49' and 40-2CD
6' above that. The sloper starts at the 47' level and slopes
down at 45 degrees to a point where it's about 10 feet above
ground. Then it scoots horizontally, still 10' above ground,
until it achieves resonance. The length has to be determined
experimentally, and probably will vary widely with the tower
configuration. I think it's about 110' long overall in my case.
There are ceramic knife switches to disconnect sections so the
antenna can be used on 75 and 80 meters.
I modeled the tower/beams/guys/wire with EZNEC, and
it shows a maximum gain of 2.5 dBi at a takeoff angle of 20 degrees,
with -3dB elevation beamwidth points of 4 degrees and 57 degrees.
Gain variation in the azimuth plane is less than one dB. Not the
best, but not bad for a city lot, at least in my opinion.
Let me know if somebody comes up with a magic bullet! 73.
Dave, K6LL
k6ll@juno.com
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