Design of Modified $4\times6$ Filtering Butler Matrix Based on All-Resonator Structures.

In this paper, two novel $4 \times 6$ filtering Butler matrices with uniform and nonuniform power distribution are proposed. The matrices, consisting of a network of coupled resonators and two phase shifters, provide power division and phase shift together with a bandpass transfer function. The analytical synthesis procedures for the $4 \times 6$ filtering Butler matrices are presented. To verify the concept experimentally, two $4 \times 6$ filtering Butler matrices, operating at 2.4 GHz, with uniform and nonuniform power distribution are designed, fabricated, and measured. Simulated and measured results are found to be in good agreement with each other. Multibeam antenna arrays are realized by using the Butler matrix, and the theoretical analysis has been confirmed by measurements of multibeam antenna arrays, which show reduced sidelobe level (SLL). [ABSTRACT FROM AUTHOR]