Theoretical Analysis and Experimental Study of Attenuation at Millimeter Wave Frequency by Water-Based Medium Radome

The attenuation at millimeter wave frequencies due to water contamination within a radar system is investigated in this paper. A model consisting of four layers of a potential contaminant is adopted in order to simulate the scattering behavior when water deposits are present with a radome. An attenuation parameter based on the Fresnel principle is proposed at 150 GHz and 298 GHz, which is supported by measurements that are obtained from pure water experiments. The attenuation due to realistic water-based contaminants in a typical outdoor environment, such as rain water, is measured and analyzed; furthermore, attenuations through sea water with different salinity is measured and analyzed. The experimental results show that the attenuation produced by radome water deposits increases with water thickness and this attenuation is not heavily dependent on the particles, such as dirt and salt, within the water-based liquid. The results presented are important in determining the feasibility of millimeter wave radar devices in realistic outdoor environments.