Topband: Transmit antenna systems and favored bearing azimuth for 160m

Tom Rauch w8ji at
Sun Oct 5 09:25:38 EDT 2003

I'm sure many people will have comments on this subject, but what I find is
the path to Europe is very consistent to the NE. The exceptions are during
summer for the northern Europeans or when the magnetic field is disturbed.

LA3XI and others are consistantly (day-after-day) skewed due east or even
southeast from here during summer, even when the A and K is very low. It is
just like clockwork, and very predictable.

VK and other long distance South Pacific signals sometimes skew without high
A or K's, but it is most common when things are disturbed. Summer or winter,
it doesn't seem to matter. I've seen ZL3REX NW path, and VK3ZL normally
waddles around from SW to W every day. At times he is NW.

JA's here seem to occasionally skew SW, sometimes while also having a clear
NW path. Stations over the pole or even just deeper into Asia (like 9M2, JT,
BY, 3W, XU, and UA0) are virtually always skewed south or southwest, it
appears to have no relationship with the alignment of the terminator. The
direction I hear also has no bearing on the directions reported by AA1K.

The XZ operations for the past few years ago were very workable in my
evenings SE path, and mornings SW path. Same for JT1, I've only heard Chak
(JT1CO) one time NE path in the evening but dozens of times SE or nearly S
at sunset.

As near as I have been able to tell I've always found the strongest receive
path (not best S/N ratio, but best absolute signal *strength*) has always
been the best transmitting path. It bears no relationship to the terminator
angle so far as I can tell.

The relationship I notice is skews occur much more frequently over long
distances, or on paths very near or through disturbed areas. The most
interesting and common variations are with northern latitude stations like
LA3XI.... and the JA's of course.

My choice with an antenna would be to have a tight beamwidth centered on the
primary path, and be able to offset broadside phasing to allow skewing of
the TX signal if required. I run a 4-square with 120/240 shift and a lower
loss phasing system than normal, and it actually has about 1 to 1.5dB more
gain than a conventional 4-square from pattern alone. The pattern is
tighter, requiring adding four broad directions. It is an eight direction
pattern with omni. The biggest problem with 1500 watts is hearing the weaker
DX stations.

73 Tom

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