| The need for the design and construction of compact and affordable sensors capable of detecting and tracking man-made targets with terrain in the background has attained significant prominence over the past decade. Such a sensor has both civilian and military applications, such as automotive collision-avoidance systems and low-altitude helicopter radar, respectively. Millimeter-wave (MMW) sensors have been proposed for these type of applications because of their compact sizes, high resolution, and their ability to work in almost all weather conditions.;This thesis contributes to the development of such MMW sensors through several specific contributions. The first entailed extensive characterization of the statistics of MMW scattering by terrain. We showed that the Rayleigh fading model is applicable for characterizing the statistics of the radar backscatter from statistically homogeneous distributed targets at low grazing angles. Also, we showed that the radar backscatter from heterogeneous terrain obeys a conditional Rayleigh distribution.;A second major contribution involved the development of analytical models for the coherent and incoherent components of MMW scattering by a rough, lossy, dielectric cylinder, and applied the results to scattering by tree trunks. Scattering by a tree trunk gained our attention because it represents the first potential type of terrain that a MMW radar is likely to confuse with man-made targets. The developed models were verified experimentally at 95 GHz wherein very good agreement with measurements was achieved. In addition, the possibility of occurrence of high radar cross section values from a trunk above a ground plane was studied and a methodology to calculate its probability of occurrence was introduced.;Also, in this thesis we introduced a new set of detection features that are based on the frequency correlation function (FCF). Based on a set of outdoor measurements and extensive analytical and numerical simulation analyses of the FCF and its dependence on relative amplitudes of the backscatter from all of the scatterers in a radar-illuminated cell and their number, we proposed a new detection algorithm. This algorithm was tested and its capability to distinguish tree trunks from the surrounding environment, including man-made targets, was demonstrated. |
