Radar Calibration and RCS Measurements

The University of Michigan has been involved in the development of calibration procedures and precision calibration devices to quantify the complex radar images with an accuracy of 0.5 dB in magnitude and 5 degrees in phase. This research began about six years ago in preparation for the Shuttle Imaging Radar-C/XSAR (SIR-C/XSAR) flights which took place in 1994. Our activities in the area of calibration of polarimetric SARs can be categorized into four areas: (1) development of calibration techniques for point targets, (2) development of polarimetric calibration techniques for distributed targets, (3) design of novel precision calibration targets, and (4) development of polarimetric calibration techniques for SAR systems based on point and distributed targets. In this investigation we have been involved in: (1) characterizing coherent and incoherent effect of the background on the polarimetric response of calibration targets, (2) analysis, design, and construction of an optimum corner reflector having large RCS, low weight, and minimum interaction with the background, (3) deployment of calibration targets and truck-mounted scatterometer systems in the Michigan Super-Site during the SIRS-C/XSAR overflight, and (4) analysis of data and evaluation of calibration accuracy (post processing).