Blocking-matrix and quasimatrix techniques for extended-null insertion in antenna pattern synthesis

Inserting extended nulls while preserving a desired beam pattern is a topic of interest for sensor array pattern synthesis in radar, sonar, communications, acoustics, etc., where nulls are needed to combat interference from known directions. Blocking-matrices can address this problem by modifying the weights forming a quiescent antenna pattern, but they require trading the degrees of freedom used for null insertion with those needed for pattern preservation. This paper uses quasi- and mixed-matrix techniques to obtain the minimal set of blocking-matrix basis vectors that best define an extended continuous null; it then presents efficient practical implementation procedures for inserting single as well as multiple extended and/or discrete nulls.