WIDE-BAND WAVE-GUIDE AND RIDGE-WAVE-GUIDE T-JUNCTIONS FOR DIPLEXER APPLICATIONS

Scattering parameters of E- and H-plane stepped waveguide and E-plane ridge waveguide stepped T-junctions are obtained using an extension of the three plane mode matching method [1]. An optimization process is applied to find the T-junctions and steps dimensions that yield low re flection coefficient in one of the T-junction arms over a wide frequen cy band. An example of the design of a wide-band T-junction diplexer i s presented. The diplexer filters are inductive window waveguide filte rs, and are rigorously modeled using mode matching and a novel two-dim ensional curve fitting method, which drastically reduces the CPU time for optimization. The diplexer optimization procedure, as well as the filter modeling method, are described. Experimental results on the opt imized T-junction and the diplexer are presented; both showed excellen t agreement with their computed optimum results, without any adjustmen ts or tuning.