Frequency selection and multipolarimetry for hard target detection

Microwave imaging of Earth from space has seen, in the last years, a huge increment of interest from many present and potential users. The main instrument for obtaining microwave images is certainly the synthetic aperture radar (SAR). The good spatial resolution associated to the all weather capability lead to consider SAR not only a scientific instrument but a tool for verifying and controlling the human daily relationships with the Earth environment. New missions have been identified for SAR as spatial resolution became lower than three meters: disasters, pollution, ships traffic, volcanic eruptions, earthquake are only few of possible objects which which can be effectively detected, controlled and monitored by SAR mounted on satellites. This paper deals with high resolution SAR frequency selection for hard target detection. Simulation results are produced for S- and X-bands, pointing out advantages and drawbacks of each one wrt the application. The improvement obtainable in detection and classification by multipolarimetry is outlined and most common technique like whitening filter discussed. S-band shows better performance in hard target detection because it combines a higher average target backscattering and a lower terrain clutter