I lose my antennas about once each year to straight line winds. Flying
branches knock them down. But if the wires are still intact I can run
the nets with the lowered antennas. Using less than optimal antennas
works; just not as well as perfect antennas. In an emergency I really
don't care about perfect performance, I simply want to contact someone
for assistance. By all means put up the best antenna you can just
remember any antenna can make contacts.
Years ago I wrote some software to display antenna propagation patterns
as a half wave dipole was lowered from 1 wavelength above ground until
it was on the ground. The results were pretty interesting. By using
the program I found many heights would work well depending on where I
wanted to contact. At less than 1/10 wavelength above the ground the
radiation patterns got rather odd but still worked for in-state comms.
Once I had modeled what was going to happen I tested it by dropping my
antennas to different heights and tested comms. Theory and practice
correlated quite nicely.
Kevin. KD5ONS
P. S. The application also modeled 1/4 wave verticals and loop
antennas. I never found the time to model the Yagi-Uda, the math got
too hairy. Using Euler's equation a few times got me through the three
antenna types I was able to model. Beating on the Bessel functions
would have taken longer than the time I had allotted to me.
K.
On 4/30/2017 1:22 PM, Bill Frantz wrote:
I have always wondered how towers hold up during earthquakes. Being
able to work with ad-hoc antennas seems a good attribute for any
emergency plan.
73 Bill AE6JV
On 4/30/17 at 11:34 AM, [email protected] wrote:
Please try NVIS on 40 or 80 meters. You'll find you can cover most of
the state with its use. Plus the antennas can be ad hoc - tossed
into trees or even an old fence line.
-----------------------------------------------------------------------
Bill Frantz | I don't have high-speed | Periwinkle
(408)356-8506 | internet. I have DSL. | 16345 Englewood Ave
www.pwpconsult.com | | Los Gatos, CA 95032
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