The electric-field Integral-equation method for the analysis and design of a class of rectangular cavity filters loaded by dielectric and metallic cylindrical pucks

Rectangular cavity filters loaded by metallic and dielectric cylindrical pucks represent a wide class of structures used for the realization of compact microwave filters for space and terrestrial communications. The electric-field integral-equation method has been applied here to develop a software tool for the design of such a class of filters. Resonators simultaneously containing a number of dielectric and metallic cylindrical pucks can be analyzed using the method presented here. Dielectric loaded rectangular waveguide filters and comb-line filters are two typical examples where this approach can be applied. The input and inter-cavity couplings realized by slots have been modeled using the proposed integral-equation method. The full-wave analysis and optimization of an entire filter can be performed using the software presented here. Dielectric and metallic losses have been taken into account and the tuning screws have been also included into the analysis. The prototype of a single resonator and complete passband dielectric loaded rectangular waveguide filter have been realized and measured to test the software, and a commercial software has also been used to validate the code. A number of examples are presented here. A very short computation time of the order of 1-s/frequency point for the analysis of an entire filter has been obtained, making the full-wave optimization of an entire filter an affordable task.