Wideband beamspace adaptive array utilizing FIR fan filters for multibeam forming

We propose a wideband beamspace adaptive array that uses FIR fan filters to construct a multibeam forming network. We also describe a method for desig ning such FIR fan filters. Approximation is achieved by combining spectral transformation and the window method such that the beam patterns including the sidelobe characteristics of the resulting fan filters are virtually fre quency independent. This is a requirement of beamforming networks used in m ultibeam forming. Fan filters designed with the proposed method are used to demonstrate that the beam-space adaptive array can suppress interference s ignals having a wide fractional bandwidth and that the array has fast conve rgence.