Design of 2-D 180° Filtering Couplers Based on All-Resonator Structures

In this letter, a novel 2-D 180° filtering coupler based on all-resonator structures is proposed. The 2-D 180° filtering coupler, composed of four 1-D 180° filtering couplers, achieves phase shifts in two dimensions with an inherent bandpass filter function. The comprehensive design methodology and synthesis approach for the 2-D filtering coupler are presented. For experimental verification, an example of a 2-D 180° coupler with fourth-order filter response is devised, manufactured, and tested. Excellent alignment is achieved between the simulation and test outcomes, which indicates the correctness of the design method.