Research On High-performance Miniaturized Microwave Components With Filtering Responses

With the continuous development of modern communication system,various microwave millimeter wave devices have higher performance requirements.As a device that can select a specific frequency signal and filter out other interference signals,the filter widely exists in a variety of microwave millimeter-wave circuit system,thus,the performance improvement of the filter is very important.Moreover,in order to meet the miniaturization requirements of RF front-end systems,filters are often used with other microwave devices for integrated design,which can achieve multifunctional components with filtering function and other functions at the same time.Similarly,the performance improvement of these multifunctional components like filter power divider,filter antenna and filter power amplifier are also of great research value.This thesis mainly studies on the performance improvement of filters and filter power dividers,and the researched performance improvement direction focuses on the miniaturization and selectivity improvement of the two kinds of devices.In this thesis,the resonator is folded and embedded to achieve the miniaturization of the device.Moreover,methods such as source load coupling and loading short-circuit coupling line structure are adopted to introduce transmission zero points to achieve highly selective filtering performance.The main content of this thesis is as follows:1.Firstly,a microstrip filter with a center frequency of 4.88 GHz is designed by using the stepped impedance resonator as the basic resonator element and the filter is miniaturized by bending and embedded the resonator element.Moreover,the transmission zero is introduced through the source-load coupling structure to achieve selective enhancement.On this basis,the single band and dual-band filters are redesigned by introducing a short-circuited coupled line structure.Both filters are introduced multiple transmission zeros which results in high selectivity and stopband rejection.A dual wideband filter is designed and implemented based on the substrate integrated waveguide structure(SIW).The filter realizes a dual-band response by combining the high-pass characteristics of the substrate integrated waveguide and the resonant characteristics of the complementary split resonant ring.In this thesis,the resonant characteristics of C-type complementary split-ring resonators and the coupling characteristics of multiple split-ring resonators are analyzed in detail,and the design flow of the whole dual wideband filter is described completely.2.Based on the previous work,two high-selectivity filtering power dividers is designed by using parallel coupling line filters and short-circuited coupled line structure.The difference between the two filter power dividers lies in the treatment of the second harmonic generated by the resonator.The single-band filter power divider suppresses the second harmonic and the dual-band filter power divider is to excite the second harmonic to achieve the second passband.Besides,both of the filtering power dividers have a high selectivity due to the introduction of out-of-band transmission zero.