Antenna Monopulse Measurement Modeling and Calibration for Improved Tracking

In an effort to more cost-effectively utilize existing assets to perform more functions, there has been a growing interest in using conventional mechanical scanned monopulse radars (normally used only for tracking single targets) to simultaneously track multiple targets. In order to maintain acceptable track accuracy, the radar's monopulse traverse-elevation response must be carefully calibrated. The ALTAIR radar at Kwajalein Missile Range does not presently correct for off-boresight errors. Since the typical 15-minute pre-mission checkout is not adequate for full calibration, there is a need for a model that can be updated using limited pre-mission checkout data. A program is described for identifying, analyzing, and evaluationg candidate monopulse models and associated calibration procedures to permit accurate off-axis tracking of depolarizing targets. The proposed program addresses our approach for (1) making the necessary calibration measurements during pre-mission checkout, (2) updating candidate parameterized polarization models using the calibration measurements, and (3) extracting the depolarization corrections from the model using a simple algorithm.