Discontinuity modeling and stepped optimization technique based design of wideband contiguous millimeter-Wave Diplexer for EW application

This paper describes the detailed design steps of wideband contiguous Diplexer using Suspended Strip line Substrate (SSS) covering the frequency range of 18-40 GHz. Good input match, low insertion loss, smooth & narrow overlap region with good selectivity and performance repeatability are major requirement for achieving high performance wide-open millimeter Wave (mmW) multiplexers. However the above requirements are difficult to achieve simultaneously especially in the mmW region where perfect input match is a primary concern over a wideband region. The design, analysis and optimization using existing Microwave simulation software's with unavailability of accurate linear schematic models and Electro-Magnetic (EM) based models with limited or no optimization feature tightened the challenge further. The step by step discontinuity modeling and optimization approach has been described to obtain the accurate and fast simulation results. The approach has been described and verified practically to achieve cross over loss of less than 4 dB and input output matching with return loss of better than 10 dB in the entire band of 18-40 GHz.