Hi all,
A quick update to my new project to improving the Arrow antenna, efficiency
wise. I wanted to see how well it would perform on gaining and losing
access during AOS and LOS. AO-27 is not a good choice since the timer is
turned on when it is well above the AOS horizon and it is switched off
before it reaches its LOS horizon. That leaves a dependable AO-51 to test
it out.
With the last setup, the OEM diplexer provided by Arrow Antenna, I would
copy AO-51 about 3 minutes after AOS and lose it about 3 to 4 minutes before
LOS. Not bad, but people were saying they worked the birds when they were 1
degree off of the horizon. I have some pine trees that could be an issue
but they are spaced far enough apart that I can work between them and I also
have to deal with the McCollough Range to the SSE of me here in Las Vegas,
NV. Today, there were 2 passes of AO-51, one at 12 degrees elevation, the
other at 74 degrees. During both passes, I began to copy the downlink about
a 1.25 minute after AOS. A considerable difference from 3 minutes. The
downlink also improved down to about minute before LOS. On the last pass I
worked KG6NUB at 0124z and LOS was 0125z and my downlink sounded fairly
good, though I was fighting desense. (That's another issue I need to
resolve.) Also, on both passes, I never once lost the downlink. No
dropouts or fades. I'm still amazed.
Another issue I came across was how wide the beamwidth is of the Arrow
Antenna between the Arrow diplexer and the new diplexer. I was wondering if
this was going to happen and it did. The reason that this happened was with
the old diplexer, the signal attenuated so much that you had to be pointed
right smack dab on the bird, a few degrees off and you lost the signal.
Now, with the new diplexer, you can point the beam in the general direction
and still copy the bird. In most cases I had to turn the beam 90 degrees
before I completely lost the downlink! Twisting the antenna to make
polarization changes makes absolutely no difference now. This also
attributes to the fact that now I'm copying the entire pass without dropouts
or fades. Makes sense. What I've regained over the lossy diplexer makes up
for any polarization differences, etc. for a better copiable signal.
Next weekend I will have to try more passes and get a feel of how much this
system has changed.
73,
Jeff WB3JFS
Las Vegas, NV
DM26