Topband: COAX RX loop question.
Jose M. Valdes R. YV5LIX
yv5lix at cantv.net
Thu Feb 5 16:43:25 EST 2004
Wile preparing for next month's CQWW SSB 160 meters contest, and since I
need a receiving antenna, I came across the coaxial loop described in the
ARRL antenna book, and it seems that if mounted outside in a short 10 foot
tower with a small rotator this could be a good option.
While reading the article I found out that it calls for 20 foot of coax and
it is said there that this is about .037 lambda at 1.810 MHz, and that the
over length should not exceed 0.1 lambda and also that "0.037 lambda is
about the maximum practical dimension if the element is to be tuned to
resonance", but at 1.810 MHz 20 foot is ~0.037 lambda in the air, and since
the velocity factor for RG-58U is .66 shouldn't the actual overall length of
the coax be 13.2 feet? (20 foot X .066 = 13.2) electrically speaking for
radio waves traveling through a RG-58U 13.2 foot will be 0.037 lambda at
Now, I'm I wrong? Or there is something that I'm missing here?
Any help will be appreciated, I would like to try this LOOP antenna but also
I would like to build it right and to obtain the maximum possible
performance out it.
73/DX Jose M. Valdes R. (Joe) YV5LIX
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