Design and Characterization of a Multiband Polarimetric Active Radar Calibrator at L, S, C and X Band

With recent developments of SAR sensors in multiple frequency bands by different space agencies, their accurate calibration is becoming equally important before SAR data can be applied to generate final application product. Active and passive radar calibrators are often used in conjunction with airborne and spaceborne Polarimetric SAR acting as ground based calibration targets with specified RCS. ARC's provide a clear advantage against their Passive counterpart in the fact that their Scattering matrix can be accurately known by design and also for the same RCS it is much smaller than a Corner Reflector. This paper describes the design and Characterization of a Wideband Active Radar calibrator, which can operate in the L, S, C and X bands. Laboratory and field measurements are performed to characterize the performance of the developed ARC for establishing its RCS stability, settability and dynamic range, as well as to evaluate its integrated impulse response. Characterization methodology for lab testing of ARC in Full Polarization mode is also presented. This development has been tested in calibration campaigns for ISRO's EOS-04 SAR and later will be used for calibration of NISAR etc.