Wide Stop-band Waveguide Diplexer Developed

This dissertation was based on the generalized Chebyshev filter synthesis theory, combined with the equivalent theory of fields and circuits and used of the high frequency simulation software aided design waveguide filters. Ultilizing waveguide field theory to analysis waveguide filters spurious responses and complete a wide stop-band waveguide diplexer with the needed development. The diplexer effectively inhibited the spurious response to the outside of second harmonic passband.Firstly, the generalized Chebyshev filter matrix synthesis theory is introduced, it was a theoretical basis for this article. Coupling matrix in the filter design played an important role, this theory used matrix rotation to obtain the required topology.Additionally, combining the theory of fields and circuits to design waveguide filters. Using this theory, the design of waveguide filters would be fast and accurate with less difficulity.Thirdly, beginning with the waveguide field theory, three waveguide approaches for spurious passband suppression were introduced: the cascade structure of waveguide low-pass filter, low pass stub coupling structure and evansecent-mode waveguide structure. The three methods were analyzed and compared.Finally, according to the index, a C-band wide stop-band waveguide diplexer was designed, debugged and tested. The final results agreed well with the simulation results. The second spurious passband suppression was at the 2.7 frequency multiplication and satisfied the technical specifications. This wide stop-band waveguide filter has certain reference value for the design of the project.