On Fri, 19 Oct 2001 11:45:06 -0500 Tom Martin <tmartin@chartermi.net>
writes:
>
> If you have a three element 10 meter beam and you can put it at 80
> feet
> or side mount it at anywhere from 40-60 feet, where would you put it
> for
> DX operation and not SS?
>
> Tom W8JWN
Here is how I would answer that question. Go to the arrl's web
site and download N6BV's latest elevation angle statistics.
While you are at it, download the freeware version of
his terrain analysis program. It draws nice elevation patterns,
even for flat earth.
Experiment with different heights to see what pattern best fits
the statistical angles of arrival to suit your operating style.
For example, from Arizona to Europe, the 10m arrival angles vary
from 2 degrees to 14 degrees.
If your antenna is at 80', it will
be 4dB louder than an antenna at 50' when the arrival angle is
2 degrees.
However, when the arrival angle is at 12 degrees, the 50' high
antenna will be 20 dB louder than the 80' high antenna.
This is why, if you have only one antenna, it should be at no
higher than about 50' on 10 meters. Otherwise, you will have a
null right in prime statistical territory, even for DX. You gain
only 4 dB with the higher antenna for those marginal 2 degree openings,
but you lose 20 dB when the band is wide open, where the higher angles
are required. Maybe this is ok for the way you like to operate. By
going through the analysis, you will be able to decide for yourself.
If you don't want to go through all that, put your 10m antenna
at 50'.
Dave Hachadorian, K6LL
Yuma, AZ
K6LL@juno.com
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