[NLRS] Microwaves today...

[jcplatt1@mmm.com]

Hi Mike.   As you know, according to theory, water absorption can play a
big role in 24 GHz DXing.    Relative humidity is temperature dependent
.... there is a ton more water in the air when its 20 degrees C and a RH of
50% compared to 5 degrees C and a RH of 50%.    As the air warms up it can
hold more water.

Check out the 24 GHz water absorption graph at
http://www.kwarc.org/10ghz/24g.html

Based on this graph, if the air temp was about 10 degrees C with a RH
around 90%, that would have been about 0.2 dB of attenuation per kilometer,
or, from you to Gene, about 43 dB of 24 GHz RF sucking water.    That may
explain in part why the path was not there.

The bad news is that 0.2 dB per kilometer isn't too bad .... it can get far
worse !    Looks like 0.1 dB per kilometer is about as good as it gets
while 1 dB per kilometer is about as bad as it gets, or a 10:1 range.
Path loss looks much better when it gets cold, really cold, as cold air
can't hold water.

73, Jon
W0ZQ