MONOPULSE RADOME ERROR COMPENSATION IN THE PRESENCE OF APERTURE BLOCKAGE

APERTURE BLOCKAGE HAS BECOME A SERIOUS OBSTACLE FOR AIR-TOAIR AND AIR-TO-SURFACE DUAL-MODE MISSILES. THE RADAR ANTENNA OF THESE SYSTEMS POTENTIALLY SUFFERS, FROM SEVERE APERTURE BLOCKAGE SINCE THE IR SENSOR AND ITS ASSOCIIATED LENS/WINDOW IS TYPICALLY PLACED ON THE RADOME OF THE MISSILE. APERTURE BLOCKAGE CREATES SEVERAL PROBLEMS FOR THE MISSILE SEEKER SYSTEM BUT THE MOST SERIOUS IS THE DISTORTION OF THENULL IN THE DIFFERENCE PATTERN WHICH PERTURBS THE MONOPULSE ERROR SIGNAL. PAST WORK HAS SHOWN THAT APERTURE TAPERING CAN BE USED TO REDUCE THE SIDELOBES OF A BLOCKED APERTURE. WE BELIEVE THAT TAPERING CANALSO BE USED TO REDUCE THE MONOPULSE DISTORTION OF A BLOCKED APERTURE. TOYON PROPOSES TO EXPLORE THE EFFECTIVENESS OF VARIOUS ALGORITHMSFOR MODIFYING THE ILLUMINATION TAPER TO PROVIDE A ROBUST METHOD OF COMPENSATING FOR DISTORTION OF THE MONOPULSE ERROR SIGNAL. WE PLAN TOUSE THE TIME-TESTED AND PROVEN TOYON NESS MODEL (WHICH COMPUTES THE E-FIELD OF SUM AND DIFFERENCE PATTERNS AS WELL AS THE MONOPULSE ERRORSIGNAL) FOR THIS EFFORT. THIS MODEL WILL ALLOW US TO SYNTHESIZE ALGORITHMS WHICH MODIFY THE ILLUMINATION FUNCTION AND COMPENSATE FOR DISTORTIONS AT VARIOUS SCAN ANGLES.