Synthetic Aperture Radar Imaging with Frequency Scanning in Azimuth Direction

There is a tradeoff between an azimuth resolution and signal-to-noise ratio (SNR) in synthetic aperture radar (SAR) imaging. One of solutions is using a spotlight mode SAR. In this mode, however, an observation area is limited compared to a stripmap mode SAR. Thus, we propose a new method using a frequency scanning antenna and steering an antenna beam in azimuth direction to solve the tradeoff without limiting an observation area. The unique and essential point of this method is a large beam steering occurs in azimuth direction on every scan in contrast to a beam steering in a spotlight mode SAR that occurs little by little through an observation.The main outcome of this study is a mathematical model of echo signals for the proposed method, and we conclude that from a result of a numerical evaluation, the method solves the tradeoff in some situations but not all, because a non-negligible side effect exists.