94 GHz band rough surface scattering characteristics based on numerical analysis

This paper investigates rough surface scattering characteristics at 94 GHz band by means of an electromagnetic field integral equation. The 94 GHz band which has the least atmospheric attenuation between 75 GHz and 110 GHz and is considered to have narrower beamwidth and wider bandwidth in general, is vigorously studied for various applications, such as, collision avoidance vehicle radar, weather radar and remote sensing with ultra wide band radar. In these applications, the scatterer such as asphalt pavement, pebbles and rain drops should be of almost the same order as the 94 GHz band wavelength. The 94 GHz band scattering characteristics are thus considered to belong in the Mie region, not in the Rayleigh region, and thereby should be unique as compared with microwave bands. From this point of view, we have initiated the study of scattering characteristics for various scattering objects (land vehicle, rough ground, grass, etc.) in order to evaluate signal-to-clutter (land clutter) ratio at 94 GHz band. In this work we carried out the prediction of 94 GHz band scattering electromagnetic wave field from rough surface with perfect conductivity for the purpose of understanding the following two points: (1) 94 GHz band radar cross section (RCS) as a function of scatterer´s roughness and (2) its polarization dependence.