Statistics an Attenuation of Microwaves by Intense Rain

An important problem in designing wide-band radio-relay systems at frequencies exceeding 10 GHz is reliability. Propagation through heavy rain is the significant factor in determining readability of the medium. Thus it is important to examine the spatial and temporal behavior of heavy rain and the resultant attenuation. Recent measurements of progagation at 18.5 GHz and 30.9 GHz, and analysis of rainfall data from the Crawford Hill rain-gauge network of Bell Telephone Laboratories at Holmdel, New Jersey, have led to an improved understanding of the rain environment. 1 - 4 Those data are used here to provide information on attenuation by rain for use in system design. In particular, the improvement in performance obtained by use of path diversity is evaluated. 5 II. S I N G L E - P A T H S T A T I S T I C S ( N E W J E R S E Y ) 2.1 The Magnitude of the Attenuation First, one must ask: What is the magnitude of the attenuation caused by heavy rain at frequencies exceeding 10 GHz? Figure 1 is a plot of 2949