MILLIMETER-WAVE PROPAGATION IN ARID LAND - A FIELD-STUDY IN RIYADH

A field study on wave propagation covering a wide range of the electromagnetic spectrum was actively running for four years in the city of Riyadh, Saudi Arabia. The region can be considered as a typical arid climate where the rate of evaporation is higher than the rate of precipitation. The study involves the operation and continuous, computerized monitoring of two millimetric wave links with radio frequency of 40 GHz, and an infrared link with 0.88-mu-m wavelength. A meteorological station is also operated and monitored. This paper presents a description of the experiment, and reports results of measuring sand storms and rain as they affect the radiowave propagation at 40 GHz and at near infrared. The effect of sand storms on propagation is studied by measuring the storm parameters; viz., visibility, particle size and size distribution, and induced attenuation due to these storms. The results are compared with long-term visibility data for Riyadh, and complete statistical analysis are given. The effect of rain is studied by measuring both rain rate and rain attenuation. Long-term rain data are utilized to derive long-term rain statistics. It is shown in particular that the measured attenuation caused by sand storms is about four times larger than the calculated attenuation at 40 GHz. The measured rain attenuation at infrared is found to be smaller by a factor of 0.3 than theoretically predicted attenuation.