Topband: Topband Angle changes at sunrise/sunset

[Tom Cathey]

Here's my observations for both 75M and 160M sunset and later evening
angles, based on 15 years playing  75M DX and only a few months doing 160M
DX -  for CT to Europe:

Using the 3el 160M vert array compared against the 160M dipole at 198',  I
notice many times they are almost equal into Europe at sunset. Later on
about 3-4 hours later the vertical is 6-12db stronger.  The optimum takeoff
angle at sunset would be maybe about 40 degrees to see this vert vs: dipole
crossover?

On 75M I notice that the 2 el quad at 190' is almost at par with the low
55' high dipole maybe 75% of the time at sunset... that really surprises me!
But later in the evening the quad is 12-15db louder according to TX reports
and receive switching back and forth. It appears that sunset from the east
coast to Eu is high angle...maybe 50-55 degrees or so to see that kind of
crossover equality.  Later on the angle is likely  down around 30 degrees or
so.

Occasionally at sunset and night time I see  "non reciprocal" comparative
receive vs: transmit reports...whereas I see no difference on receive and
they say they see 10db difference, and other times I see 10db on receive and
they see nothing on TX. This happens maybe 10% of the time.  I understand
that sometimes each station has a different optimum path, thus different
angle hops, etc.

Also, during even slight auroral conditions all antennas are about equal
into Europe and directivity usually goes to hell, though sometimes the
flutter sound is more pronounced when beaming NE as you'd expect. Flutter
will sometimes disappear completely when beaming Southwest, especially on
75M.

For what it's worth.

73,

Tom, K1JJ
CT