|[AMRadio] Non-ordinary Antennae|
jpl15 at panix.com
Mon Jan 29 21:26:20 EST 2007
Brett (et al) I will add that, while I still think that two adjacent
parallel coaxial cables do *not* make a balanced *anything* (I am
researching the facts to back up my big mouth) my antenna system here at
KB6SCO is a horizontally-disposed rectangular / nearly square loop of
about 480 feet circumference, realized with #14 copperclad wire, attached
to the tops of my backyard fence at the 5' level, and the eaves of the
back of the house - using 4" long cuts of 1/2" PVC pipe, drilled through
on one end to accept a 3" drywall screw, and slotted near the other end
for the wire. It is thus a quasi-NVIS - I call it my "RF Fountain" - watts
go straight up and then spray everywhere.
At the feedpoint of this loop, which is also the (little-used) gate into
the back yard - I use a dual #8 barrier strip, to which is attached
450-ohm plastic-jacketed commercial ladderline ("window" line) - and
carried on the same PVC insulators into the shack (in the garage) via a 4"
hole I popped in the stucco with a hole saw.
I currently run a Viking Valiant into an Ameritron ATR-15 tuner, thence
into the balanced feedline. SWRs anywhere on 80/75 that I'm licened for
can be brought down to 1.1:1, and there has never been any kind of
heating/arcing that I'm aware of. 160 is fairly touchy, but 1.3:1 can be
achieved. 40 tunes up nicely, and on 20 I can also get down to about
1.3:1. 15 and 10 just plain don't work - so I don't use those bands.
I've had two sympathetic neighbors agree to alert me to any
interference, there is none - however this is also a completely new
housing development and all utils are underground - everyone has cable or
dish-TV - that also helps.
This antenna is stable, quiet, has garnered QSOs all over the western
hemisphere on 80M, and is only barely susceptible to the monster static
charging that we are prey to here in the high desert of northern Nevada.
And a lot of folks took great pains to tell me that I'd never get a
watt out, angle of incidence this, radiation resistance that... so I just
made myself familiar with the rudimentary math involved, a bit of antenna
design theory... hey, it's Only A Hobby!!!
PS: Wait til I get the 1KW RCA B'cast rig up and making Power... ;}
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