[Antennas] Question

Fri Jan 23 01:25:11 EST 2009

On 1/23/09 12:51 AM, Chris Boone wrote:
>> Friend in a restrictive area wants to do this....run a loop around the 
> house at the eave....not sure what the length would be so assume non 
> resonant on any band....and probably 1200 sq ft in length.......if fed 
> at a "middle" point, any idea what the approx Z would be on the HF 
> bands??? We were discussing how to feed it; if it were ME, I would put 
> an auto tuner at the feedpoint and run coax back to the rig.....he has 
> a 3yr old manual tuner with coax and balanced out but doesn't want to 
> run balanced through the wall or under the window in plexiglass, 
> etc..sooo he wants to use 4:1 balun at antenna and then 10-15 ft of 
> RG8 to tuner...
>> Any thoughts on that guys??? He could probably get away with it but I 
> think a 4:1 may not be right.......your thoughts, comments and if 
> anyone has modeling software to model it on 80-10, I would appreciate it.
>> Chris
>> WB5ITT
>
You're right, the auto-tuner at the feedpoint is the way to go. A 
length of coax that short isn't going to hurt him that much. I think 
the feedpoint impedance might be a bit low for a 4:1 balun, a 1:1 balun 
to keep RF off the coax sheild might be a better choice. If you could 
borrow an antenna analyzer, you'd have a better idea...
73s, AJ4LL
-- 
"The tree of liberty must be refreshed from time to time with the blood of patriots and tyrants. It is it's natural manure."
Thomas Jefferson, 1787.
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