The effects of ground permittivity and surface roughness on multi-path measurements at K-band

A number of automotive radar systems have been designed with application to adaptive cruise control, road surface monitoring, accurate speed measurement, and potential application to collision avoidance. In order to construct these high-tech radar systems for the automotive market, a thorough understanding of the residential and highway environments in which they would operate is required. In this paper, a versatile open-ended waveguide measurement technique is used to determine the effective dielectric permittivity of various ground types. From this information, K-band LOS (Line-Of-Sight) propagation above different ground materials are calculated and compared with outdoor measurements. Here the influence of ground permittivity, surface roughness, and ground layer thickness on K-band propagation is presented.