----- Original Message -----
From: "Al Williams" <alwilliams@olywa.net>
>
> Although the books and EZNEC show that the 72' antenna should have about a
> 20db null as compared to the 38' antenna, I have yet to observe a
> received signal on the 38' beam as strong as when on the 73' beam. Of
> course this comparison is when both antennas are pointed in the same
> direction and the received signal is coming from a location pointed to by
> the beams.
>
> Located in western Washington and probably having a reasonably good ground
> (wetland toward the east) and a flat terrain, I expected that the lower
> antenna would often produce the stronger signal but it hasn't ever.
>
> Why?
>
My observations over the last few years suggest that in
periods of low solar activity that very low angle signals
dominate the high bands (at least for F-layer propagation).
If ever there is a time to have high antennas and a QTH with
terrain favorable for low-angles, this is it. You may have to wait
for the next solar cycle before you find situations where the
antenna at 38' starts to play better than the one at 72'. The
good news is that you can point 2 el at 38' in another direction
from the 72' antena and use it to work multipliers or use it
for SO2R.
73, Mike W4EF...........................
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|