Compact 3-D Printed Phase-Shifting Coupler With Decoupling Column and Defected Ground Structures for Millimeter Wave Applications

In this brief, employed with the selective laser melting (SLM) of three-dimensional (3-D) printing, a compact waveguide phase-shifting coupler (PSC) is proposed. The new structure has the same function as a 3 dB 90° (hybrid) coupler and a −45° phase shifter but a minimized size, which could decline the components of the conventional
$4\times 4$
Butler Matrix from ten to four. The miniaturization is attained with a modified
$TE_{201}$
-cavity and a tiny decoupling column (DC). The theory of circularly polarized components (CPC) and mass constructed by the periodic current in rectangular waveguide associates it with the primitive design of the transmission line model and explains the further miniaturization directed by DC. Besides, non-radiative DGSs are slotted as heat sinks with the propagating center routes of the current. The designed 45°/−135° PSC at 28 GHz has a good agreement between simulation and measurement.