[MLB-WIRELESS] Smoke...

[Tony Langdon]

> how about rain?
> 
> I know about ice (anyone want to repost that link about the 
> iced up antenna?)

Rain, yep, though at 2.4 GHz, it would need torrential rain.  More likely is
wet foliage causing attenuation of the signals, rather than the rain itself.
As the frequency goes up, rain scatter losses become MUCH more significant.
> 
> humidity?
> I know gps signal timing changes are used to track RI changes 
> in the upper atm 
> to log humidity changes.  how do they affect ground links?

Humidity tends to cause loss at very high frequencies (10's of GHz).  At 2.4
GHz, humidity and temperature gradients can cause bending of the signal.  An
inversion will cause it to bend downwards and follow the earth.  It's also
possible to get "ducts" - cool layers sandwiched between warmer ones at
altitude, which can trap signals like a waveguide.  When this happens, every
VHF/UHF ham and UHF CBer drools...  (I have worked Tasmania with 1/2 W from
a handheld under these conditions on 438 MHz!).  Also popped a few CB
repeaters in Tassie too that night. :)

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