NEARFIELD ADAPTIVE ARRAY MEASUREMENTS

IN ORDER TO DETERMINE THE FAR-FIELD PROPERTIES OF AN ADAPTIVE ARRAY ANTENNA SEVERAL NEAR-FIELD MEASUREMENT TECHNIQUES TOGETHER WITH AN ANALYTICAL MAPPING OR EXTRAPOLATION ARE PROPOSED AND ANALYZED WITH RESPECT TO ACCURACY AND ANECHOIC CHAMBER IMPLEMENTATION LOGISTICS. STEADY STATE PERFORMANCE INCLUDING GEOMETRY SENSITIVITY AND RADIATION PATTERN EFFECTS SUCH AS NULL DEPTH, NULL WIDTH, SIDELOBE LEVEL, AND MAIN BEAM DEGRADATION AS WELL AS THE TRANSIENT ADAPTATION TIME OF THE ADAPTIVE ALGORITHM ARE MEASURED. THE PROPOSED DESIGN AND ANALYSISADDRESSES FULLY ADAPTIVE ARRAYS AND PARTIALLY ADAPTIVE SYSTEMS OF SIDELOBE CANCELLERS. THE NEAR-FIELD ELECTROMAGNETIC INTERACTION BETWEEN THE SIGNAL SOURCE, WIDE-BAND JAMMER SOURCES, AND TEST ARRAY IS EXACTLY AMENABLE TO A LINEAR MATHEMATICAL MODEL. THE CROSS-CORRELATION BETWEEN ELMENTS IS CALCULATED USING A COMBINATION OF INTEGRAL TRANSFORMS AND RANDOM SIGNAL METHODS, TOGETHER WITH CLASSICAL ELECTROMAGNETIC MODELS SUCH AS THE PLANE WAVE SPECTRUM TO REPRESENT THE NEAR FIELDS. HOWEVER, THE ADAPTIVE PROCESSOR COMPONENT OF THE ADAPTIVE ARRAY SYSTEM IS TYPICALLY NON-LINEAR, WHICH IMPLIES THAT THE ANALYTICAL MAPPING FOR NEAR-FIELD TO FAR-FIELD PERFORMANCE IS GENERALLY SYSTEM DEPENDENT.