|[AMRadio] I'm not an antenna expert|
jpl15 at panix.com
Wed Jan 11 11:43:30 EST 2006
I don't even play one on TeeVee...
So, in advance of a lot of EZNec work (and I don't have the experience
with that program to derive much 'good' out of it right now) - I'd like
to ask what may seem to be a rather obvious HF antenna question.
Due to the usual reasons - my HF antenna is a loop suspended from my
backyard fence - approx 430' total, closed loop, 5' off the ground, fed by
450 ohm ladder line back into the shack, using an Ameritron ATR-15 tuner
to match the system to my Valiant. The tuner and transmitter are bonded
to a very heavy ground system via an 8' stake less than 3' from the gear.
There is no ground system under the antenna, other than that which Nature
provided - and with the current winter conditions, the ground is rather
wet and conductive.
This antenna system exhibits the following SWR:
160M - 1.3:1
80M - 1.1:1
40M - +3:1
20M - 2:1
15M - +3:1
10M - +3:1
The tuner capacitors end up being all-the-way-meshed on the
'misbehaving' bands - not so on 160, 80, and 20.
So I'll see Y'all on 3880 and just fergit the rest. ;}
No but seriously folks: obviously the feedpoint resistance is outside
the tuner's ability to cope with it at various frequencies.
I'm thinking the first unscientific experiment might be to go to the
opposite side of the loop from the feedpoint and cut it into a big
horizontal bent dipole - mainly because that will take about 45 seconds to
accomplish - one of the benefits of having one's entire antenna at
But I'd like to get some other opinions - I know there's an electrical
Pattern here from the info - and I have some other ideas based on that.
And no, I can't put up a "real antenna" so I'm pretty much comiited to
making this one work as well as I can. Until I move the QTH to somewhere
with a few acres and room for Lots of Wire.
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