miso@sushi.com wrote:

SPLAT! has modes to predict radio signal strength. I'm just doing line
of site for now, but the program can handle Fresnel (sp) zones and
such. There are professional programs for such modeling.

Look, for example at the area east of Groom Lake,
between the dry lake and Tikaboo. The model shows
that as "dark" but I guarantee you'd have comms
from Tik to the floor of the valley there.

It's just really hard to predict what RF will do.
RF is even weirder than light. Especially around
rocks, the rocks act exactly like a waveguide
in a microwave transmission line. The voltage
and the current component of the wave are 90
degrees to each other. But once it starts bouncing
and refracting, those components change places,
enhance/cancel each other, evoke voodoo, all
kinds of weird schitski.

When we installed 800 systems in Arkansas,
we discovered that the average length of
the region's pine needles was nearly exactly
a quarter wave at the frequency. Singly and
in small groups, they acted like radar chaff.
But in thousands of acres of forest, they
acted like an elevated ground. That would
tend to pull the pattern toward the earth.
We'd hear mobiles from several hundred
miles away and we could actually communicate
both directions with them. Got really spooky
when "One-Oh-Nine" was 10-8 but we knew that
our "109" was doing something else.

We ended up scrapping the 800 system and
returning to high band VHF. We lost the
GE and MOTO radios that had been on and
functioning for decades. Had to go to
moto flood board (SMT) "disposable" radios.

Price, progress.


Lumpy

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