Microwave Rain Gage

This proposal describes a plan for the design and development of line of sight and area averaged rain measurements using microwave techniques. The line averaged (and area covered) could be made variable, from as low as 100m (100m x 100m) to several km. The individual units can thus be used for both local measurements as well as for extending the observation over rain-cells. The techniques might be extended using multi-frequency and other techniques to obtain independent estimate of rain size distribution.Both microwave attenuation and phase-shifts are potential candidates for measure rain rates. Microwave attenuation increases with frequency for up to 100 GHz. The choice of appropriate frequencies is important and optimization may become necessary in terms of available technology, cost and accuracies. The proposed effort describes a plan to develop a versatile instrument for measuring attenuation and phase at several frequencies. Experiments performed using the instrument will allow us to infer the optimum system parameters for rain measurements. A detailed engineering design for the development of such a system will be provided during Phase I.