Albert

I'm a little experienced with failure in trying EME on 2 meters. I'm not
a scientist, but have some information that might help you decide which
antenna is best for your situation.
I'm not able to calculate the amount of steering thats available with a
long V antenna. I couldn't even predict the antenna's radiation pattern
shape. If the antenna pattern has about equal beamwidth in both elevation
and azimuth, a 20 DB gain antenna will have about a 20 degree beamwidth (as
I remember).
You probably know all this, but--
The moon rises and sets at a slightly different azimuth each succeeding
day. The azimuth direction to the moon on the horizon might vary by about
50 degrees per year.
I consider the moon to be about 1/2 a degree wide. It will rise at "its
diameter" each 2 minutes.
It looks to me like you'd have a few minutes of 'max gain' each year, and
theres no way for you to predict _*when*_ because the "takeoff angle" at 2
lambda is unpredictable.
If my thinking about *where the moon is* is about right, I predict that
you wont be satisfied with an antenna that isnt more stearable than the V
for moon bounce.

I've read about a guy who made a long yagi antenna by suspending it on
ropes rather than 'booms'. I wonder if you might be more satisfied with a
yagi that you could "roll up" when icy weather approaches.

Jerry






"Albert" wrote in message
...


Hi Ian,

Thanks for your comments.

My hope was to use a v beam instead of a rhombic.

The V is relatively easy to steer, especially if the performance
doesn't change much if either leg is moved. Note that I hope to leave
one leg of the beam fixed and steer the az by varying the position
(and the V angle) of the other leg. Not sure how much changing the
angle of the V impacts the performance, which is why I asked for
someone with modeling software.

My hope was to exploit the high gain, simple construction (but poor
receive) of the V for transmit only and to use the modest sized FO
yagi for receive only.

If I can get 19 or 20 db from a big V beam, I can probably tollerate
the limited operating time as well, Q's with big guns should take only
minutes and medium sized stations should be workable in a 20 minute
window.

If the computer model predicts a usable gain, I'd like to try putting
one up.

Regards,

Art



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