Dual Frequency Measurements of Rain Induced Microwave Attenuation on a 2.6-Kilometer Propagation Path

Rain-induced attenuation at centimeter and millimeter wavelengths is a function of drop-size; conversely, a measure of drop-size can be obtained from multi-wavelength measurements over a common propagation path. As shown in Fig. 1, a 2.6-kilometer path, shared by both 18.5 and 30.9 GHz, extends to the southeast of Crawford Hill, Holmdel, New Jersey. Both of the receivers are located in the same building at Crawford Hill; the equipment has been reported elsewhere, 1,2 it will not be discussed here. In addition to obtaining a measure of the drop-size distributions by examining the ratio of the 30.9-GHz attenuation to the 18.5-GHz attenuation during rainstorms, sufficient data are available for a statistical examination of the rain-induced attenuations for both frequencies. In the following, the cumulative distributions of attenuation at 18.5 and 30.9 GHz will be discussed individually and then related one to the other. 2599 2600 T H E BELL SYSTEM TECHNICAL JOURNAL, OCTOBER 1971 Fig. 1--Map showing the propagation path of 2.6 km used at 30.9 and 18.5 GHz.