The Feasibility of a Compact Polarimetric Synthetic Aperture Radar for Polsar and Polinsar Applications

Nowadays it is widely recognized that SAR polarimetry (POLSAR) and polarimetric SAR interferometry (POLINSAR) add a valuable contribution to promising applications in many fields of remote sensing. SAR polarimetry uses the information embedded in the polarization state of electromagnetic waves scattered by the target; as an example, this technique has been used for vegetation mapping, classification and bio-physical parameters retrieval. POLINSAR technique combines SAR polarimetry and SAR interferometry and associates a scattering phase center to each resolution cell. The interferometric phase at different polarizations can yield information on the height of the target in the cell through suitable scattering models [1, 2]. With reference to forested areas, promising applications of this technique are biomass estimation and multilayer topographic information retrieval [3]. Both POLSAR and POLINSAR require full polarimetric (FP) SAR sensors and interferometric acquisitions. Full polarimetry from space implies system constraints to cope with data downloading rate, size of the processed swath and power consumption. To overcome these limiting factors, a new approach for SAR polarimetry, called compact polarimetry (CP), has been proposed. In the CP architecture, the SAR transmits either a circularly polarized wave (π/2 mode) or a linearly polarized one oriented at 45 degrees (π/4 mode), and receives at both horizontal and vertical polarization. A central issue in remote sensing is to assess the performance of a CP SAR sensor with respect to a fully polarimetric configuration.