Interesting reading some of the comments on this topic.
I have been working DX on 160m for 50 years (I started young LOL!) . . .
The one thing I have ALWAYS noticed over the years is that the propagation
is OFTEN very selective on 160m. I will be hearing other EU stations working
people that I can barely hear . . . but also vice versa.
Years ago, when conditions were much better, I often had SSB QSOs with North
American stations . . . there would be 2 or 3 of us here in Europe, and
several stations in different parts of the USA. Being in a multi-station
phone QSO made it much easier to compare signals (than on CW) . . . and what
very often happened was that the path between just TWO of the stations would
be good, but poor between the others.
To me, this is all because the Propagation on 160m is very different to even
80m. I believe that much of the time the contacts are via ducting -
inter-layer bouncing of the signals. Getting access in and out of the duct
varies a lot, depending on exactly where you are located. Sometimes there
may a physically small opening, others times it is very wide.
One of the reasons I also believe that most long-distance QSOs on Top Band
are via ducting is the fact that I have ALWAYS used a high angle antenna
(low dipole) for working DX, yet had consistently good reports. If the
propagation was like on 80m - where you nearly always need a good low-angle
antenna to put out a decent DX signal - then that wouldn't be the case.
I believe that getting into the duct occurs at fairly high angles (maybe 45
degrees), and that's the reason I have always done pretty well working DX
with my high angle antennas.
Since I have had a separate vertically-polarised receiving Loop for 160m
(the past 2 years) it has been interesting to compare DX signals on that, as
against my Dipole. There is no doubt that when my signals in NA are at
their strongest (as seen on RBN sites as well as received QSO reports),
received signals are better on my Dipole than the Loop. To me, that
indicates when I have a really good duct opening, as the high angle antenna
is actually better on receive.
Just how and when the ducting occurs on 160m I obviously have no idea, but I
suspect it is sometimes tied in with the effect of daylight on the layers,
and why SOMETIMES grey-line propagation is good (but not always)
Roger G3YRO
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