G'day all,
This year I had a clear-out of some old magazines and went carefully
through them, looking for nuggets of 1.8MHz information. One of the best
pieces I found came from a Bill Orr W6SAI 'Antennas' column in CQ August
1977, based on correspondence Bill had with Stew Perry, W1BB.
In the correspondence, Bill apparently asked Stew's opinion on a range of
antenna topics connected with 160m and the article contains several antenna
systems used by well-known operators of the time, including G3RPB, W4DAA/9
and Stew himself.
Although W1BB nominated a quarter-wave vertical tower with a LARGE system
of radials as the most effective single-element transmitting antenna, Stew
added the rider that the antenna should be located over marshy ground/very
close to the seashore and by "large number of radials" he meant at least 200.
However, if Stew was limited to just one antenna, his first choice was an
165 - 170' inverted-L, fed with coaxial cable via a series capacitor over
as many radials as possible, giving both horizontal and vertical polarised
radiation. His second choice would be an inverted vee dipole, "if it was
high enough".
Now Stew's idea of high wasn't necessarily all that high it seems, but he
did have a high opinion of the inverted vee dipole, calling it the best
all-round 160 metre antenna. He thought that a 1.8MHz inverted vee dipole
should have a minimum height of 50 - 70' at the apex, with the ends
clearing the ground by 15 - 20'.
While the inverted vee dipole wasn't quite as good as a high vertical with
a good earth system, Stew rated the inverted vee dipole as an excellent
performer for an average location with poor soil. He apparently liked the
inverted vee because "it provides radiation at many different angles, one
of which is bound to hit the ionisphere for good propagation."
It is interesting that W1BB seemed to believe that having either one
transmitting antenna with a wide variety of polarisation angle and giving
both horizontal/vertical polarised signals, or separate antennas that gave
a similar mix, was a good way to go on 1.8MHz.
Stew used both inverted-L and inverted vee antennas, having a 2-element
inverted vee beam at his famous Point Shirley W1BB/1 water tower site, as
the long-time 160m operators on this reflector will be aware.
Other topics covered in this article by W1BB and W6SAI are small loop and
underground/underwater (!) antennas for reception. It is a fascinating read.
On a final note, I recently had a RST 559/569 QSO with Declan EI6FR around
my sunrise. Declan was using 50W to a shortened/loaded inverted vee dipole
(100' long), with its apex at 35' and the ends at 15'. I picked Declan out
of a fairly large pile-up - who says 1.8MHz always needs big antennas!
Vy 73,
Steve, VK6VZ
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