Sometimes crazy things happen on 160.
I've had extensive experience with a 100 foot shunt fed, top loaded
tower over 100 radials and an inverted V, apex at 75 feet. Actually not
very inverted with the ends at 20 feet. I had both antennas up for
several years. Most of the time the vertical won by a wide margin or was
the only antenna I could work the DX with.
One day when I was in the middle of making changes the vertical wasn't
available and neither were my Beverages. I heard 9M2AX CQing on the long
path and he was 579 on the inverted V! I got him on the first call, even
beating out VE1ZZ with his four square. I think that was the one and
only time I ever got past Jack on working DX. That's some crazy stuff!
There were some days the mainly horizontal wire would win out to Europe
at my sunset, and some similar sunset anomalies with VQ9 and 8Q7. But
the vast majority of time the vertical was the clear and decisive winner.
73,
Paul N1BUG
On 1/23/22 6:32 PM, David Gilbert wrote:
Recent threads here have pointed out the adverse effect of poor ground
conductivity on vertical polarization versus horizontal polarization,
but as best I understand things there is some advantage to vertical
polarization due to the gyro-frequency of electrons in the atmosphere.
Bob Brown, NM7M (SK), was known worldwide for his studies on 160m
propagation, and his tutorial on HF propagation in general, and 160m in
particular, is noteworthy:
http://www.astrosurf.com/luxorion/Radio/nm7m-hf-propagation-tutorial.pdf
I live on a steep hillside with a wide and very deep ravine running down
across my property, and in order to work a DXpedition to 3B9 (2003 or
2004 or so) I ran a 2 element wire yagi across that ravine and it just
luckily pointed to 3B9. I had to feed it with a few hundred feet of
RG-8X coax (thicker coax would have been too heavy) to a spot where I
could park my car, and although I used a 400 watt solid state amp I was
probably feeding only about half that to the antenna. I easily worked
the 3B9 on 160m, though, and was the furthest west station to do so.
Most hams only heard the 3B9 for five or ten minute openings, but for
several days I could easily copy them for periods ranging from 30 to 55
minutes. I posted my success here on TowerTalk, and NM7M sent me a post
telling me that he calculated that for that path vertical polarization
had an 11 dB advantage over horizontal polarization on 160m.
The gyro-frequency effect decreases significantly at higher frequencies,
but for 160m it seems to be pretty important ... at least for some
paths. I've heard lots of hams claim that verticals rule on 160m, and I
suspect that it isn't only because putting up a suitably high horizontal
antenna is so difficult.
I guess my point is that maybe we shouldn't be dissuaded from putting up
a vertical antenna on 160m just because we have poor ground
conductivity. Control the return loss in the near field as best we can
(lots of great comments here recently on how to do that) and hope the
gyro-frequency effect helps with the far field effects.
Caveat: I don't think that the theoretical gyro-frequency advantage
holds true for all paths. I think east-west paths are different than
north-south paths.
73,
Dave AB7E
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