Null synthesis in irregularly spaced sparse antenna arrays

Sparse array antennas have the advantages of wideband performance with less mutual coupling. Large sparse arrays are used for radio astronomy as they provide low cost large aperture compared to the filled array counterparts. Due to the large number of elements involved and complex array geometries optimization of such antenna arrays takes significant convergence time and prove to be computationally expensive. In this paper it is shown that the use of subarrays will reduce the convergence time for null synthesis that is essential to avoid radio frequency interference. Excitations are determined for assumed irregular sparse array geometry using a hybrid optimizer to obtain pattern nulls in prescribed direction with array gain constraints.