Has anyone tried this?
I remember seeing an article in either the ARRL Handbook
or Antenna Book about a recieving antenna for 160m. It is
a 'magnetic loop' made of coax with a small section of the
braid removed at the midpoint and resonated with a trim-
mer capacitor. The article showed a picture of the loop
in a diamond shape supported by a bamboo cross.
I made a similar recieving antenna for 80/75m with a piece
of RG59 and supported it on a picture frame and microphone
floor stand. It could be rotated (inside the shack) and
about 20% of the time would help recieve stations by nulling
the noise. Without it the station was unreadable (S/N).
Here's what I'm thinking about:
I have a piece of 7/8" hardline made into a 10ft square.
I was origionally going to make a similar 'magnetic loop'
for recieving and put it on a pole, rotating it with a small
TV rotor. How about replacing the 'trimmer cap' with high-
voltage capacitor(s) and resonating it for xmitting? I believe
the hardline can handle the voltages but what about the capac-
itor? Has anyone made a homebrew high-voltage capacitor for
this type of use? Has anyone out there ever tried this type
of loop for xmitting on topband? (Vacuum variable caps are
very expensive, but I will keep my eyes open at the upcomming
Hamfests) I may build it using the trimmer cap and then remove
the trimmer for measurement. Then I'll know how much capacit-
ance it takes to resonate the loop.
I'm presently using a doublet 86-1/2 ft. (x2 = 173ft.)
in an inverted vee, center-fed with 450 ohm window line.
I think the loop should have a lower take-off (radiation)
angle and the ability to rotate it may help for DX as well.
Any suggestions - ideas?
-------------------------
de Scott / W4PJ w4pj@w4bkx.ampr.org
-73-
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