Limtex:
Regarding question number 4(F) .
"On account of the basic interaction of electromagnetic waves with water in liquid form, raindrops cause absorption, scattering and depolarization phenomena. The first two result in signal attenuation (not to be confused with either water vapor attenuation or attenuation by rain clouds) and increase in sky noise temperature. These effects are quite noticeable above 10 GHz..."
Source: Reference Data for Engineers: Radio, Electronics, Computer and Communications. (Page 27-34) Eighth Edition. Sams Publishing (1995)
This book is similar to the Physicians Desk Reference. While much of the material goes rapidly out of date with the continuing advances in state of the art, it is still well worth having for the foundation information alone.
The actual amount of attenuation (reduction in signal strength) caused by rain depends upon the frequency and the rain rate. You can make two generalizations: (1) the higher the frequency, the more attenuation and (2) the harder the rain the more attenuation. Point number two trips people up at times. For example, in which city would a microwave path be more effected by rain, Seattle or Dallas? Most people would say Seattle. However, the answer is Dallas because while it does not get as much annually as Seattle, the rain is much harder. (thunderstorm downpours versus constant drizzles).
There is no magic to calculating this for any city. (the equations and graphs are in the above book). In the US, we've been collecting rain data for over 100 years and the attenuation effect by frequency and rain rate are known.
The foregoing has large impact on valuation for P-MP broadband wireless. However, that's a post for another day (if I haven't already put everyone to sleep.)
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