Research On Microwave Components With Filtering Responses

Microwave components with filtering responses,also called filtering microwave components,are multi-fuction components,which are implemented by integrating the filtering responses to the conventional various microwave components.In order to suppress the interferences in the front-end system as well as the inter-modulated or harmonic signals,many microwave filters need to be added.Compared with the conventional method by simply cascading the filters,the filtering microwave components can not only reduce the circuit size,insertion losses and design procedures,but also enhance the filtering responses.In this thesis,a series of single-ended/balanced bandpass filters(BPFs),filtering power dividers(PDs),filtering push-pull power amplifiers(PPPAs),resonator-based antenna array as well as filtering microwave crossover is introduced.The main contributions of this thesis are as follows:(1)A novel terminated coupled-line structure is presented.The design principles of impedance matching and filtering responses are theoretically derived.Introducing different types of terminations,two single-ended wideband BPFs and a balanced wideband BPF is proposed,with high passband selectivity and good stopband rejection performances.Then the design examples are simulated and measured to verify the proposed structures and design theory.This part of work is published in IEEE Transactions on Microwave Theory and Techniques.(2)The harmonic suppressed dual-transmission line structure with miniaturized size and harmonic suppression is introduced,which can replace the conventional quarter wavelength transmission line.The related design procedures and filtering responses are extracted theoretically.By replacing the conventional quarter wavelength transmission lines of wideband BPF with proposed dual-transmission lines,a wideband BPF with good passband selectivity and high out-of-band rejection is designed and measured.This part of work is published in Electronics Letters.(3)A series of wideband/narrowband filtering PDs with high selectivity and good stopband rejection is introduced based on terminated two-and three-conductor coupled-line structures.The detailed design parameters and filtering responses are theoretically derived.The design examples are simulated and measured to verify the proposed structures and design theory.This part of work is published in Electronics Letters,Microwave and Optical Technology Letters and Journal of Electromagnetic Waves and Applications.(4)The wideband/narrowband filtering PPPA topologies are firstly introduced.The signal filtering,unbalanced-to-balanced transforming and impedance matching characteristics are integrated in one circuit,which can miniaturize circuit size,enhance the output power and efficiency.The proposed topologies are verified by simulation and measurement.This part of work is published in Electronics Letters as a feature article.(5)Four-element antenna array for Octa-band smartphone applications is presented based on resonator-based impedance matching network,which can greatly improve the low-band bandwidth and impedance matching characteristics.This part of work is published in International Symposium on Electromagnetic Compatibility.(6)A compact wideband crossover with filtering response is presented,with separated operating frequencies in two transmission paths.The key difficulty of conventional crossovers when handling two widely separated frequency ranges in different transmission paths is successfully overcome.A filtering crossover design example is fabricated and measured to verify the proposed structure.This part of work is published in Microwave and Optical Technology Letters.