A CALIBRATION ALGORITHM FOR CIRCULAR POLARIMETRIC RADARS

Since circular polarimetric radars can be used to assess the relative contribution of odd-bounce and even-bounce scattering to the response of targets and to implement novel schemes for adaptive rain clutter su ppression and radar pulse compression, they are increasingly used in a pplications such as radar meteorology, biophysical and geophysical rem ote sensing, and radar navigation. Although methods for calibrating li near polarimetric radars are widely known, they cannot be used to cali brate circular polarimetric radars until account is taken for the diff erent form of the response of calibration targets when measured with r espect to a circularly polarized basis. The response of three standard targets used to calibrate linear polarimetric radars (an odd-bounce-r eflector and two even-bounce reflectors with different angles of rotat ion about the radar line-of-sight) does not yield a unique solution to the calibration equations. If, however, the odd-bounce reflector is r eplaced by either a circularly polarizing or linear polarization selec tive target, the calibration equations can be solved.