Polarimetric Measurements for Sentinel-1 and Radarsat Constellation Mission using Reference Point Targets

Abstract:
The paper focuses on polarimetric measurements executed for two C-Band SAR missions: Sentinel-1 (S1) and Radarsat Constellation Mission (RCM). RCM is able to operate as a quad-pol system which transmits alternatingly H and V polarization pulses and receives H and V simultaneously. In contrast to this, S1 is implemented as dual-polarization system which transmits either H or V polarization for a specific acquisition and receives both H and V polarization simultaneously. For this purpose, reference point targets have been used to allow a comparison of the impulse response function derived from the different polarization channels. While trihedral corner reflectors allow to compare co-polarized channels only, transponders are used for analyzing all four polarization channels (HH, VV, HV and VH). In order to enable a comparison of all four polarization channels also for S1, longer time series of acquisitions over stable reference targets have been acquired. The results show that the polarization channels are well balanced for both SAR missions. The channel imbalance between the polarization channels is low for all pairs in particular between co-polarized channels (HH-VV) but also for cross-polarized channels (HV-VH).