Analysis And Design Of Novel Microwave And Millimeter-Wave Waveguide Filters And Diplexers With Compact Configuration

Microwave and millimeter-wave filters and diplexers are important components for channel selection and signal separation in many communication systems. Their electrical performances are crucial for the overall system design. Low-insertion loss, high return loss and high slope selectivity are simultaneously required for filters. Moreover, these filters should be compact, low-cost, mass-producible and tuning-free. Among the large variety of possible filter structures that potentially satisfy some or all of the above criteria, only few are really suitable for low-cost mass fabrication.In this work, novel E-plane filters and diplexers based on cross-coupled resonators or over-moded cavities are analysed and designed. A highly flexible class of filter structures is achieved which are suitable for microwave and millimeter-wave applications as low-cost, mass-producible, high performance and compact components.First, the Mode Matching Technique (MMT) and the Finite Element Method (FEM) are presented. They are the most appropriate numerical techniques for the analysis of structures introduced in this work.. It allows the technique to perform the analysis of multiple and successive discontinuities in a modular fashion.Low-cost and mass-producible folded E-plane filters with finite transmission zeros are analysed. Source-load coupling and/or standard cross-coupling are introduced in the folded structure to generate finite transmission zeros. The filters based on E-plane and ridged waveguide technology exhibit pseudo-elliptic transfer functions with high slope selectivity. They are highly compact and much shorter than traditional E-plane filters. These filters can be fabricated by photolithographic or electro-deposition techniques with high accuracy and repeatability.Then, novel, low-cost and high performance direct-coupled E-plane filters and iris-coupled filters are analysed. The new designs utilize over-moded cavities and also exhibit pseudo-elliptic transfer functions. These filters are suitable for low-cost mass-fabrication. The slope selectivity and the stopband of the filters are further improved by utilizing a combination of source-load coupling and over-moded cavities in the same filter.Finally, new, compact millimeter-wave diplexers which employ cross-coupled E-plane filters and E-plane filters with over-moded cavities are analysed. The resulting diplexers require fewer resonators than conventional E-plane diplexers to achieve comparable performance. Therefore, they exhibit lower insertion loss and are much shorter than the conventional designs. In addition, the manufacturing advantages known from E-plane technology are maintained.