Research On Multimode Resonator And Its Application To Microwave Device

Based on the systematic analysis on the structure and transmission characteristics of multimode resonators,novel dual-band Bandpass Filters(BPFs),differential BPFs and parallel-feedback oscillating circuits are proposed and investigated which meet the needs of miniaturization,multiband,low cost and high performance in modern wireless communication systems.The main works and innovations in our study are summarized as follows:(1)A dual-frequency filter which shows low insertion loss,controllable coupling strength and easy process is designed with an Substrate Integrated Waveguide(SIW)cavity loaded by Complementary Split-Ring Resonators(CSRRs).Another dual-band filter is achieved with a dual-mode SIW resonator loaded by an E-shaped slotline resonator which features low insertion loss,adjustable center frequency and good out of band rejection.In this design,a miniaturized design method using E-shaped slots is proposed which is proved by the experiment.(2)A dual-band SIW differential filter is achieved with the feeding lines placed on two metal layers.The first Differential Mode(DM)passband is constructed by the dual-mode SIW cavity etched with an air box.The second DM passband is achieved by the CSRRs loaded on the top metal layer of the substrate which makes the DM center frequencies adjustable.This filter features compact size,good selectivity and deep Common Mode(CM)suppression.(3)The Complex Quality Factor(Qsc)of the filter is systematically analyzed and studied.Narrow band SIW BPFs based on multimode resonators are designed separately by improving the group delay and the unloaded Q factor.Two low phase noise parallel feedback oscillators are then achieved based on these filters.The oscillators designed using these methods have the advantages of low phase noise performance and high values of FOM(Figure Of Merit)which are validated by the simulations and measurements.(4)Two push-push oscillators using differential BPFs which are based on multimode resonators as frequency selective elements are presented and analyzed.Its stable oscillating condition is proposed using equivalent circuit models and even-odd mode analysis.The basic characteristics containing low phase noise,good fundamental suppression and high stability can be easily obtained.