Experience gained from calibration of the SAR-580 system

The techniques necessary to perform an absolute calibration of the airborne SAR-580 system are described. The calibration method eliminates the effects of all the system components, including the image processor and the method of power measurement from an image. It involves the use of both an internal calibration signal generator, and absolutely calibrated corner reflectors. The techniques are well illustrated at X-band. It is also found that the antenna polar diagram depends on its orientation with respect to the airframe. For experimental reasons the results are less satisfactory at C and L-band. The absence of digital data giving the absolute orientation of the antenna is a fundamental weakness of the system.