Hi Richard,
I'll make one final phasing post, I'm sure Bill doesn't want the
reflector cluttered up and this has eaten up my limited time lately. I
appreciate this forum, and don't want to abuse it so I'll keep this
useful to everyone phasing receiving antennas, not just 1026 users.
I've been using and designing phased receiving antennas since the
late 70's in various applications, so I'll do my best to be accurate.
> vertical, I couldn't do much at all with the "1026". I looked at the
> 1026 users manual & read that both antennas should be of the same
> polarization for the unit to operate correctly.
The text says "distant" noise or signals. Similar polarization is
important for phase and level stability over time. Despite folklore...
mixing a horizontal antenna with a vertical is real trouble on sky-
wave circuits. Fading, averaged over a short time, actually
increases. (Remember Beverages are vertically polarized systems,
despite the plane of the wire!)
When nulling stable local signals, you can use any combo of
antennas. Only one thing is important, both antennas must hear
the same unwanted noise. Ideally the noise antenna should hear
only or mostly unwanted signal.
That's why an antenna that nulls well on groundwave might be a
dog for sky-wave.
> aux antenna gain settings can't be more then about half way up. I haven't
> yet been able to enhance any signals... regardless of what antennas I am
> using.
Enhancing signals requires both antennas to have similar S/N
ratio's, and ideally they would have similar patterns. That's true if it
is a Beverage and a Four Square, two K9AY loops, two regular
loops, or whatever being mixed. Vertically polarized antennas mix
well with other vertically polarized antennas. Since my four-square
has a similar pattern to a pair of Echelon staggered Beverages,
they mix almost perfectly!
Remember if you combine one poor S/N antenna with a good S/N
antenna in an effort to enhance signals, you will almost certainly
make the good antenna become worse!
Mixing in a poorer S/N antenna is great for nulling local noise, but
not peaking distant signals!
I mix three Beverages with a four square, using any combo that
works best. Sometimes the improvement is 15 dB or more.
Sometimes it won't help, but mixing anything vertically polarized
with my dipoles is almost always a real bust for signal
enhancement.
If you don't have a lot of space (1/2 wl or so) between antennas,
end-fire is almost always the way to go. End-fire arrangements
provide the greatest receiving improvement in limited space.
If you have lots of space, broadside can work just as well.
> I'm wondering if it would be possible to build some kind of
> graphical tuning indicator.... perhaps by using a dual channel scope
> looking at the detected outputs from both antennas at once.
Remember to accurately detect phase, the signal has to be
somewhat noise free. If we can't determine phase, we could do a
random hunt and look for highest S/N ratio in the detected output.
Unfortunately, our ears are probably the best indicator of S/N when
the signal is weaker than noise. The easiest solution is a very
directional antenna. Someone recently posted the best analysis of
S/N of various antenna models I've seen on this reflector, assuming
noise was evenly distributed. I wish I could remember who it was!
73, Tom W8JI
w8ji@contesting.com
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