Hello Ink, Bob, Peter, Bob, Dick, Jim, Tom, Javier, David, & Jim,
Many thanks for all of your e-mails...
I hope you don't mind a "group" response like this, but it sure does save wear
& tear on the fingers, strain which is better left to manoevering the Vibroplex
keyer...! Thanks much for your interest in the grounded half loop for 160, &
for sharing your experiences with them (all them POSITIVE, by the way, for
those who have never used one!).
For the uninitiated, there are several references to the aerial: the first, by
John Belrose (VE3CV), appeared in the (I believe) May 1982 issue of HAM RADIO,
a copy of which I do NOT have. There was also a co-written piece by Belrose &
Doug DeMaw in the September 1982 issue of QST, and a short description of it in
(I believe) the second installment of the ARRL's ANTENNA COMPENDIUM.
I have two here: the first is oriented north-south, & looks like a long
inverted "V" from the horizon (the apex is 50' high on a tower)...the second is
oriented east-west, & looks like an inverted "U" strung between two tall trees
in the yard. Looking at each antenna separately, the feedpoint is at one end of
the wire, right at ground level. There is a ground stake as well at this point,
and a 1/4-wave counterpoise wire (comprised of insulated wire, laid atop the
ground) for each band, i.e. 160-, 80-, and 40-meters.
The opposite end of the wire is terminated in a ground stake, and it, too, has
a 1/4-wave counterpoise wire for each of the three bands.
The system is fed with RG-62 coax, which is low loss, and which I happened to
have an abundance of! A "...quick & dirty" check of the SWR on the "...inverted
'V'" half loop revealed the antenna to be resonant just above the BC band---it
was flat across 80-, 15-, and 10-meters. On 20-meters, it was 2:1, and on
40-meters it was 2.25:1. I used the formula 1005 / f (MHz) / 2 for the "V", and
found the wire to be too long...for the second "U" loop, I used 468 / f(MHz)
which was more accurate.
It is an EXCELLENT harmonically operated antenna for DX on 40, and, I suspect,
80. I've used both for U.S. QSOs on 160-meters, but haven't heard any DX
there---yet! The Top Band season is still early for me here, but I'm certainly
preparing for it.
One thing for sure, it DOES seem a LOT quieter, noise-wise, than other
sky-hooks tried here...I guess because of the grounded end...? By NOT grounding
the far end, it would become a half-square of sorts (i.e. a 2-element Bobtail)
for 80-meters. Also, I believe that as one goes UP in frequency with the end
grounded, the thing starts to radiate more off the ends, than in a line
opposite to the plane of the wire. BTW, one of the articles quoted the front to
side ratio of being only some 3 db, or so---I put the second loop up opposite
to the plane of the first more to take advantage of directional characteristics
on 40-meters, than anything else...
I guess that about sums it all up. If you have room for an 80-meter half
square, then you've already got the fixings for a 160-meter half loop! I guess
a relay arrangement at the far end would enable you to take advantage of the
features of BOTH of these wonderful wire antennas...
Keep that soldering iron/propane torch warm, & my very
~73!~ Eddy VE3CUI - VE3XZ
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