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Old September 13th 07, 12:17 AM posted to rec.radio.amateur.antenna
Richard Clark Richard Clark is offline
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First recorded activity by RadioBanter: Jul 2006
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Default Slinky dipole HF antenna recommendations wanted.

On Wed, 12 Sep 2007 22:20:43 GMT, Dave Oldridge
wrote:

I made a 160m loop out of LMR400, using the capacitance of the inner-to-
outer conductor to resonate it. Made it two turns and wound a gimmick
match out of flat 4-wire phone cable onto it to fire it up. Very narrow,
but reasonably effective. Better than a hamstick, I think. It's about 3
feet in diameter.


....

Yes, my 160m loop is almost too narrow for SSB.


Hi Dave,

Radiation resistance for a 1 meter loop at 1800 KHz is 23 microOhms.
If I were to interpret your BW to be 2 KHz (an antenna Q of 900); then
the Ohmic resistance would be 0.0225 Ohms (0.002 Ohms/foot). This
resistance is on par with #13 wire which has considerably less surface
area than the LMR400.

The added resistance resides, undoubtedly, in connections (or maybe
the gimmick); and if you drove it out, you might find your loop
suitably more efficient for CW-only. Unfortunately, it might become
an arc-gap transmitter.

As an aside, I can't visualize the gimmick's relation to the
inner/outer conductors. You have any close-up pictures?

73's
Richard Clark, KB7QHC