Polarimetric Synthetic Aperture Radar Imaging With Radially Polarized Antennas

A polarimetric 3-D synthetic aperture radar (SAR) imaging method using a radially polarized antenna is described. The advantages of the radially polarized antenna, mainly that polarimetric SAR imaging can be performed without requiring additional measurements compared to traditional SAR, are discussed. A general target model is developed that includes information about target orientation and degree of polarization (i.e., how well and in what direction the target polarizes a signal). Image reconstruction algorithms were developed to allow polarimetric imaging to be performed with radially polarized antenna imaging data, enabling the estimation of target orientation and degree of polarization. The effect of scan step size and scan aperture size is studied on the accuracy of the estimation of these parameters, and guidelines were established as to the proper step size and scan aperture size to be used to keep estimation error below a specific threshold. Subsequently, a radially polarized antenna was designed, fabricated, and used to image several samples containing various types of point targets, by which the capability of this technique to enable accurate estimation of target orientation and degree of polarization is successfully demonstrated.