Propagation investigations at 85 GHz

Attenuation during precipitation at the frequency range of 85-90 GHz is investigated, due to a relative minimum in the atmospheric attenuation that exists in this region which could be useful for microwave communications. Attenuation is calculated for the case of spherical rain drops, and results are presented for raindrop temperatures of 0, 10, and 20 C and for various rain intensities. The attenuation is also calculated for raindrops with spheroidal forms using a point-matching technique. Theoretical results are compared to experimental observations, showing good agreement, and the frequency distribution of the rain attenuation at 85 GHz is also derived.