Scalable Multibeam Antenna Arrays Fed by Dual-Band Modified Butler Matrices

A concept of dual-band multibeam antenna arrays that allows for efficient utilization of a common aperture has been proposed. The presented antenna arrays allow for achieving N-independent beams pointing at N different directions at higher frequency and N-independent beams at lower frequency pointing at N/2 different directions and having two orthogonal polarizations. As feeding networks, novel modified Butler matrices (BMs) have been proposed in which directional couplers having different properties in two frequency ranges have been for the first time utilized. To confirm the theoretical analysis, a dual-band multibeam antenna array fed by a modified 4 × 4 BM has been developed operating in 2.4 and 5.2 GHz frequency ranges.