A novel five port waveguide structure

Abstract

A compact five-port waveguide structure consisting of three rectangular ports, one coaxial port, and one circular waveguide port is proposed. The scattering matrix in an ideal case is derived using the symmetry properties of the structure. If the circular port and coaxial port are matched, the five-port waveguide structure is automatically matched. The two connected inserted coaxial probes, frustum and coaxial transition are used for matching the five-port waveguide structure with relatively wide bandwidth. The theoretical and experimental results are basically consistent with each other. With the circular port connected to the load, the five-port waveguide structure turns to be a reciprocal TEM mode to three-way TE 10 mode power divider. Measurements indicate that from 8 to 9.6 GHz, the return loss at three rectangular ports and coaxial port is less than −20 dB and −17 dB respectively. The isolation between three rectangular ports is higher than 20 dB. The volume of the five-port waveguide structure is as small as 1.5 λ×1.5 λ× λ.