Cruciform directional couplers in H-plane rectangular waveguide

This paper suggests a very compact waveguide directional coupler with a tight coupling of 3-dB or so, which is composed of two cross H-plane rectangular waveguides having two metallic posts in the square junction and an inductive window at each port. The metallic posts are set symmetrically along a diagonal line of the cross region mainly to make for the directivity properties, and the inductive windows are arranged properly at each input/output port near the junction to realize a matched state. Actually, several couplers are successfully designed based upon this concept. Additionally, the design procedure is validated by em-simulations (HFSS) and experiments. The present coupler is marked by a compact coplanar structure, four right-angled ports and ease of realizing 3-dB coupling.