Investigation of attenuation by rainfall at 60 GHz

Attenuation at 60 GHz is investigated on a 680 m vertically polarised link, with two fast-response raingauges and a dystrometer. Variations in attenuation for a given ground rainfall intensity are seen to be caused by drop-size variations. This conclusion is reached after conversion of point rainfall rates to path rainfall rates using a synthetic storm model, when the resultant variation of attenuation with path rainfall rate is seen to follow relationships predicted from the dystrometer. Nevertheless, on the average, the Laws/Parsons drop-size distribution is seen to be remarkably good for predicting attenuation from ground rainfall rates. Fading for one year was in excess of 15 dB for 10¿3% of the time. By inference, radio paths of 2 to 3km should thus be possible at 60GHz in the UK.