Two partially adaptive antenna array techniques for interference elimination

Fully or partially adaptive antenna array (AAA) techniques are designed to reduce the effect of interference and jamming signals. This is done by automatically steering nulls in the array field pattern directed towards the direction of arrival of the interfering signal. We present two simple and easy-to-implement partially AAA techniques to eliminate the effect of interfering signal when its direction of arrival is known. The first technique is based upon controlling the amplitudes of the signals at the end-elements of the array. This is done via a proposed algorithm that adjusts the weights of these elements to take one of three preset values. The technique is suitable to steer a null only within the range of the first sidelobe of the array. The second technique utilizes an auxiliary parallel array composed of 2N elements and is capable of steering a deep null at the direction of any sidelobe. This is done by controlling the weight coefficients of all elements of the auxiliary array. A performance criterion is proposed which is based upon equal weight coefficients for all auxiliary elements. In this way, the array has one degree of freedom, i.e. capable of steering only one null in the direction of arrival of interference. Satisfactory results are obtained via computer simulation results of the two techniques.