Waveguide Different Frequency Diplexer Computer-aided Design

Using of the mode matching method (M.NM), this dissertation is to research the CAD computing technique of waveguide diplexers working at different frequencies and design an specific software of the waveguide diplexer used in microwave and millimetrewave communications. According to the user designing demands, such as the center frequencies, relative bandwidth, stopband attenuation and the minimum ~assband return loss, the software can offer the necessary structure parameters fabricating this kind of diplexers. This involves the mddal scattering matrix of three appropriate key building block structures to be combined the E-Plane metal-insert section, the H-plane iris discontinuity and the H-plane T junction. In order to achieve the satisfactory performance, we should use some efficient optimization methods, the optimization process takes all relevant influences of the complete diplexer structure rigorously into account.Finally utilizing this software, we analyze and design a H-plane Tjunction diplexers working at Ka-band, Relatively good agreement between measurements and theory may be stated. Allowing for the metal wearing down, the increase in passband insertion loss and the excursion at center frequencies are inevitable.