[TowerTalk] simultaneous Horizontal and Vertical antennas

[Tom Rauch]

> To which I respond:
>
> Aachem's razor says the simplest answer is the most
likely.
> It IS true that some contest stations will take a low yagi
and
> aim it stateside, to help hold their dx frequency.
Simplest way
> to do it is to split the stack, and sacrifice 3dB.  3dB
isn't
> going to make a lot of difference on the dx side.  I've
done it from
> several stations.  It is sometimes effective.

All of the time a practice like this severely increases
fading where signal levels from the two antennas are close.
It may reduce the number of people operating on or near the
TX frequency, but everyone should consider it also increases
fading in a broad unpredictable area.

 > Secondly....with respect to the original concept of
running parallel
> vertical and horizontal antennas to get multiple
polarizations...
> twaddle!

Doesn't work. What you get is a skewed pattern with wider
beamwidth and less defined polarization. In every direction
the resulting pattern is a single polarization that is the
vector sum of the two fields in that direction.

The ionosphere will scramble the polarization, anyway...what
> he's doing is simultaneously exciting high and low
angles...(assuming
> the vertical has a decent ground system.)  He's also
destroying the dipole
> pattern.

As the above statement points out, the concept of thinking
of this as two totally isolated and independent signals is
wrong.
The actual result is it simply tips or tilts the
polarization of the pattern in every area where each antenna
has significant radiation.

Sometimes we want to transmit a broad beamwidth signal, but
the best solution is to just design an antenna that does
that and understand doing so severely increases fading in
the wide area (angle and direction) where both antennas have
significant FS.

> I'd bet he'd get better results by switching between them
and picking
> the better antenna at any given moment.

I bet that also. The reason broadcast stations quickly
abandoned 5/8th wave verticals is the combination of high
and low angles caused by the high angle lobe that appears
with the 5/8th led rise to severe fading outside of the
strong groundwave area of the antenna. This effect was so
severe they actually called shorter verticals "non-fading
verticals".

How you tune and load each amplifier plus other less
esoteric things like feedline length control where the new
nulls are as well as where the new main lobes are formed.

73 Tom