Research And Design Of Miniaturized Substrate Integrated Waveguide Filters

With the development of science and technology,the application of modern communication technology has also changed with each passing day.Since the formal commercialization of 5G communication industry in recent years,the most prominent feature is that the miniaturization degree and performance requirements of the filter have become higher.SIW as a new structure,the filter designed by this structure is very suitable for today’s communication system.Starting from the theoretical research of SIW structure,this paper introduces the miniaturization design method of SIW filter,summarizes and innovates,and uses several miniaturization methods to design two miniaturized SIW filters:（1）In order to solve the problem that the traditional SIW filter occupies a large space in the communication circuit,a design method of miniaturized SIW filter using L-shaped slot structure is proposed.In this method,the L-shaped resonant slot is etched on the top metal plate of the QMSIW resonant cavity,and the resonant frequency of the basic mode TE₁₀₁ of the QMSIW cavity moves to the low frequency by using the mode shift technology principle of slot disturbance,thereby improving the miniaturization of the SIW structure.Based on this method,a second-order quasi-elliptic response band-pass filter with a central frequency of 2.6GHz and a relative bandwidth of 8.6%is designed.In the actual test,the filter has good passband characteristics,the return loss is better than 22d B,the insertion loss is better than 0.72d B,and there are transmission zeros in the upper and lower stopbands outside the passband.The overall performance of the actual test is excellent,which is very in line with the design standard of miniaturized SIW filter.This design method provides a new design idea for the miniaturization of SIW structure and broadens the way to realize the miniaturization filter.（2）Aiming at the application requirements of C-band satellite communication system,a design method of dual-band SIW filter with miniaturization and high selectivity is proposed.This method provides the first passband of the filter by etching the L-shaped resonant slot on the top of the QMSIW,and the second passband by using a new right/left-handed structure.The L-shaped resonator is equivalent to a quarter of the wavelength resonator,which can stimulate the basic mode in the cavity to produce low frequency response;compared with the traditional structure,the new right/left-handed structure increases the cross-finger capacitance value and reduces the resonant frequency.Both structures can improve the miniaturization of SIW filter.In addition,as a resonant unit,three transmission zeros are introduced outside the passband by cross-coupling method,which improves the selectivity of the filter.Through processing and testing,the center frequencies of the dual-band bandpass filter are 3.9GHz and 6.2GHz,and the relative bandwidths are 3.3%and 2.1%.The attenuation between passbands is better than 74dB,and the stopband rejection is better than 64dB,indicating that the proposed filter has the characteristics of small size and high selectivity,which is very suitable for integration in the front-end system of satellite communication.The paper has 48 pictures,5 tables,and 86 references.