Adaptive Feed Control Using the Completely Overlapped Subarray Antenna

The radiation pattern of the Completely Overlapped Subarray Antenna can be calculated. Knowledge of the phase and amplitude of the contribution from each element can be used to determine an appropriate weight for each element to achieve a desired pattern. The 16 feed elements on Face B of the antenna allow pattern control at 15 discrete points in the pattern. Success in using this method requires an accurate determination of the individual element contributions. Random phase and amplitude errors cannot be sensed, and, therefore, cannot be compensated for. If the approximate angles of arrival of jamming signals are known, and the number of jammers is smaller than the number of elements in the locating array, a tan loop behind each element can determine the noise covariance matrix. A quiescent noise power level is assumed, and the adjoint of the matrix calculated. When discontinuities occur in the pattern, they indicate the directions of arrival for jamming signals. The pattern of the Overlapped Subarray Antenna may then be changed to place nulls in the directions of the jammers. (Author)