Cascade Techniques Of SIW Dual-mode Filters

Substrate Integrated Waveguide(SIW) is a novel structure of microwave transmission line which integrates the advantages of rectangular waveguide and microstrip line, such as high Q, low loss just like rectangular waveguide; small size, low profile, low cost and easy to be integrated like microstrip. This present paper applies the technology of SIW into the design of filter, and introduces several kinds of high-performance dual-mode band-pass filters. The main content and contributions are as follows:(1) Processing the object of dual-mode filter with punched perturbation. During the processing, the parameters of the filter were optimized to satisfy the processing requirements. Design a dual-mode filter that is excited in new way, and study the coupling feature. This paper adopts the rectangular SIW structure ( the length is not equal to the width), and then use the difference between the length and width to perturb the field and excite the filter to be dual-mode. thus the dual-mode filter is designed.(2) Besides, this paper applies two methods of excitation, and analyzes the performance of each method.(3) Study the filter's cascade. This paper cascades the cavity filter which is perturbed by diagonally punctured and fed by non-coplanar form. In the research, both coplanar cascade and non-coplanar cascade are tried, and it is observed that the feeding point in the original one-order filter would change the performance of perturbation. Therefore, this paper gets this feeding point back into the cascade structure, and improves the performance efficiently.In addition, this paper analyzes several coupling forms in cascade structure and lists the coupling effect of each parameter.