Design And Implementation Of Substrate Integrated Waveguide Bandpass Filter

To make better use of spectrum resources and deal with the complicated electromagnetic environment,the filters with better frequency selection and signal isolation have become increasingly demanding. Meanwhile, the popularity of mobile devices is driving the development of miniaturized filters. Substrate integrated waveguide(SIW)is a novel planar circuit transmission line, It utilizes reasonable arrangement of the metallized vias and some other structure to achieve an approximation of the traditional waveguide structure, using the common planar circuit processing techniques. SIW combines the advantages of traditional waveguide and planar circuit structure, and its own unique structural features.The SIW bandpass filters are designed by analogy to the rectangular waveguide. According to this idea,the SIW bandpass filter were completed quickly and efficiently in the K-band and X-band. First of all, the characteristic of SIW and the relationship between the SIW and traditional metal waveguide were studied. And a K-band E-plane waveguide filter was designed. the ideas and methods of waveguide filter designing was analyzed and summarized. Second, inductive metallic-Via SIW filters in K-band and X-band were designed by analogy to the design of rectangular waveguide. Third, a method is presented to improve the SIW filter band rejection. Using the bandstop characteristics of the defected ground structure, adding specific defect ground structure in SIW filters’ input or output can significantly improve the ability of band rejection. And the simulation analysis shows this method is effective and feasibleExperimental results show that A filter of 1.2GHz bandwidth is obtained for 15 dB return loss from 19.18 to 20.32 GHz. the attenuation is more than 50 dB from 16 to 18 GHz, more than 20 dB from 18.3 to 18.7 GHz, and more than 30 dB from 21 to 25 GHz. compared with the rectangular waveguide filter, the Size of SIW is reduced by about 50%.