Null control pattern for circular antenna arrays

Circular arrays of equispaced isotropic elements are considered. For these structures, we propose a new technique that allows placing nulls at prescribed directions of interference in a given array pattern. Precisely, the problem is to determine the array pattern which minimises the mean-square distance from the assigned pattern, while satisfying the null constraints. The technique that we present is very simple to be implemented. It involves the inversion of small matrices and makes use of the DFT (Discrete Fourier Transform) to exploit the symmetry of the structure.