Design And Implementation Of High Performance Bandpass Filters Based On SIW Technology

As a new kind of guided-wave structure,the substrate integrated waveguide(SIW) not only have low radiation loss, high quality factor, high power capability, small volume and low weight that inherited from the metal rectangular waveguide and microstrip line, but also have the characteristics of easy processing and integration. Those characteristics make SIW technology widely used in academia and industry. Thus, it has been an important research direction to design high performance filters with SIW technology.Firstly, the main method of microwave filters design、the basic theory of SIW technology and all kinds of microwave devices that based on the SIW technology are systematically introduced; Then we focus on discussing the propagation characteristics of SIW and the structural design of the SIW-to-microstrip transition;We have also simulate and analyze the transmission characteristics of various coplanar transition structures, which laid the foundation for the study of SIW bandpass filters.Secondly, several familiar defected ground structures(DGS) are proposed in this dissertation, and we emphasis on the analysis of the equivalent circuit and transmission characteristics of the winding DGS. On this basis,a bandpass filter using winding DGS is designed by combining with the high-pass transmission characteristic of SIW structure and the low-pass transmission characteristic of DGS, while the filter have the merits of compact size、easy integration、low loss and high frequency selectivity etc.Finally, the paper put forward a new method to design high performance bandpass filter by using dual-plane resonant cells(DP-RCs). The DP- RC filter is developed by giving attention to both the surface and metal ground of SIW structure, that is to say, the filter is made by loading the U-slotted structure on the upper surface of SIW cavity and etching the H-shape fractal DGS on the metal ground. Based to the optimal simulation results, a DP-RC bandpass filter is fabricated and simulated by vector network analyzer. The measured results and the simulation results are in good agreement, which further proved the correctness and reliability of the method to design bandpass filters by using dual-plane resonant cells. Compared with the traditional SIW filters, the proposed DP- RC bandpass filter can greatly improve the overall performance of the filter and reduce the occupied area of the filter circuit, with some engineering application value.