| With the rapid development of wireless communication,there is an urgent need for miniaturization,multi-band and high-performance filters.Resonators,as the basic components of filters,are an important aspect to achieve this goal.In the conventional filter designs,the modes other than the dominant mode have a negative impact on the performance of the filters,as every resonator has multiple modes.This work aims to eliminate the negative effects of this feature to a certain extent,and even use this feature to design extremely miniaturized,multi-band,and high-performance filters.The proposed miniaturized multimode patch resonator has more advantages than the currently concerned Substrate Integrated Waveguide(SIW)resonator.In particular,the proposal and application of the miniaturized mode make the designed filter have extremely compact size and excellent performance at the same time,which promotes the development of wireless communication technology to a certain extent.The research contents of the paper are summarized as follows:1.The mode distribution in patch resonators is analyzed in detail,and the generation mechanism of the miniaturized mode——the LC mode,is proposed.2.A design method of miniaturized multimode bandpass filter(BPF)based on multimode patch resonator is proposed,and the mode control method in Isosceles Right-Angled Triangular(IRAT)resonator is analyzed in detail.By utilizing the LC mode and the perturbed modes in the IRAT resonator,miniaturized BPFs are achieved.The port regulation method is proposed to suppress the high-order modes,and the miniaturized BPF with high out-of-band suppression is realized.3.The design method of cross-coupled multi-band BPF based on multimode patch resonator is proposed,and the coupling mechanism of IRAT resonator is analyzed in detail.By utilizing the LC mode and the TM100Z mode in the IRAT resonator,third-and fourth-order cross-coupled high performance dual-band BPFs are realized.4.The mode bypass coupling mechanism in the IRAT resonator is analyzed in detail,and a design method for realizing high performance multi-band BPFs based on bypass coupling is proposed.By utilizing the LC mode,the TM100Z mode,and the TM110Z mode in the IRAT resonator,second-and third-order direct-coupled triple-band BPFs are realized.The split-band technology is also exploited to achieve fourth-order cross-coupled quad-band and sext-band BPFs.5.Mode suppression method is proposed to design balanced BPFs with high common-mode suppression according to the mode distribution in multimode patch resonators.Based on IRAT,circular and semicircular patch resonators,single-band,dual-band,and broadband balanced BPFs with high common-mode suppression are achieved.The proposed design method further realizes the miniaturization,multi-band,and high performance of the filter design,which has greater advantages than the existing designs,and has certain reference significance for engineering applications. |
