Effect of microphysical characteristics of rain on frequency scaling in microwave band

Frequency scaling concerns the variation of propagation effects with respect to frequency. The objective is to find the relationship between attenuation at a given frequency from the attenuation measured at another frequency, generally lower. Two different kinds of frequency scaling model, corresponding to different interests, can be considered: Long term frequency scaling, describes the relationship between attenuation for the same probability level. It allows studying the design of system operating at high frequency bands (Ka or V band) from the performances of existing systems operating at lower frequency band (Ku-band). Short term frequency scaling or instantaneous frequency scaling (IFS), describes the relationship between simultaneous attenuation at different frequencies. It allows performing uplink power control, where the attenuation on the uplink is estimated from the attenuation measured on the downlink. The different contributions: rains, gas, clouds, which contribute to the total attenuation, depend on frequency in different ways, that´s why this technique is most satisfactory when one cause predominates. The present study focus on IFS of rain, the aim is to deduce the attenuation due to rain for one frequency (higher than 40 GHz) from the measurements at another lowers frequencies (Ka Band).