A quasi butler matrix with 6×6 beam-forming capacity using 3×3 hybrid couplers

Abstract

A novel 6×6 beam-forming network with the topology structure and the properties similar to Butler Matrices is represented in this paper. Two 3×3 hybrid couplers are adopted as the substitution of traditional 3dB-90° hybrids to introduce the factor of 3 into in this network for changing the numbers of ports and beams from conventional 2n to 6. Moreover, one kind of 2×2 hybrid couplers with quasi-arbitrary phase-difference is utilized as well to eliminate using fixed phase shifters in this design for a smaller size and a lower loss. As an example, one proposed 6×6 network working at 5.8GHz has been designed, simulated, fabricated and measured. Good performances in matching, isolations, equal power divisions, coherent phase differences at all ports have been achieved. The possibility of improving structural flexibility of Butler Matrices by employing 3×3 hybrids is demonstrated in this paper.