Topband: 160 meter antennas

Mon, 12 Nov 2001 13:56:24 +0000

I had a similar experience with a "U"-type antenna on
160m, one big  difference being that the horizontal length
of mine was 140ft instead of 100ft.  At one time, I had an 80m
half square up- about 68-70ft vertical wires and 140ft horizontal.
I had an 80m LC tapped tank for feeding on 80, but used to
switch onto it often as a 160 receiving antenna. Despite the
received signals being pretty well attenuated, I found that the
apparent S/N was pretty good. (This 'array' was just about end-
fire into Eu)  One day I got the bright idea to wind up a big tank
inductor for 160m on an ~4.5in dia ceramic form with coax cap.
I was astonished to learn, upon comparing with my full size
160 loop with apex at 110ft, that this antenna was pretty much
keeping up with the delta into Eu on 160. Much of the time
they seemed about dead even- this despite the fact that the
horiz. wire had a *wicked* sag in the middle- I bet it was only
about 35ft above ground in the center (the expected highest
current point on 160).  At the time, I figured I
must have had both vertical and horizontal components aplenty,
and just chalked it all up to the idea that often 'short'  3000 mi.
paths like western Eu feature surprisingly high angles of arrival
on 160m. Anyway, I figure the "U"-type antennas might be a
bit of a sleeper among the topband crowd, what with there
being so many far better skywires to choose from!  BTW my
half square had just a 3 by 5ft hardware cloth counterpoise at
the fed end for a ground, and floated at the far end, with no
ground whatsoever. Amazing!  Either it was working surprisingly
well that season or else my delta is working a *lot* worse than
I thought.  :o)    Another possible explanation might be that the
two antennas were coupling. Maybe the Delta, which was
substantially 'behind' and to the SW, looking towards Eu, was
acting as a reflector (or vice versa).
Today, I figure the delta puts me maybe halfway up the east
coast food chain (at best) on 160m- sure, plenty of guys walk on
me with 4-squares- but I figure this implies the half square was
working a heck of a lot better than I would ever have dreamed of.
One other aside- I found that elevating the bottom half of my
delta from about 8-10ft average to around 15ft average made a
big difference in performance. Also, the BW dropped
measurably, as I would expect. This suggests that it might do
even better up through about 25-30ft min. elevation, were that
possible.    73, David K3KY