Research On The Theory And Design Of Novel Planar Wideband Filtering Power Dividers

With the development of the technology of microwave wireless communication,microwave passive network plays an important role in both antenna feed networks and radio frequency circuit systems.With the gradual miniaturization of electronics,the smaller size and higher performance of the microwave circuit systems are required.Therefore,the multi-functional microwave component that combines the different functions of two or more microwave components into one component is proposed.In particular,the co-design of filters and other microwave components,which is in large actual demand,is the most valued.This dissertation gives more attention to the co-design of two key components in microwave passive systems: filter and power divider and proposes a series of filtering power dividers with good port-to-port isolation for wideband,dual-band,multi-way and unequal applications.The main contributions of this dissertation are shown as follows:1.A novel topology of wideband filtering power divider is proposed.For the traditional two-way Wilkinson power divider,its topology could be divided into two parts: two quarter-wavelength transmission lines used to meet impedance matching and isolation resistor utilized to isolate the two output ports.In order to further expand the passband bandwidth of the power divider,the multi-mode resonator is used to replace the each quarter-wavelength transmission line of the Wilkinson power divider.In this way,the number of resonance modes in the passband could be increased to expand its passband bandwidth.Furthermore,the frequency selectivity of power divider is enhanced by introducing the multi-mode resonators.Due to the introduction of the resonators,the isolation achieved by simply mounting an isolation resistor between the two output ports is not ideal.Therefore,by introducing a new isolation network,the energy absorption efficiency of the isolation resistor is improved,thereby achieving a good wide isolation band.Finally,the wideband filtering power divider with good isolation is achieved.2.A novel topology of wideband multi-way filtering power divider is proposed.The multi-mode resonators are utilized to expand the impedance matching bandwidth and achieve filtering characteristics of the power divider.Secondly,the proposed isolation network is utilized to improve the bandwidth of the isolation band.Finally,the wideband filtering power-dividing topology is presented,and it has been successfully extended to multi-way power divider.To verify the proposed design method,the prototype three-way wideband filtering power divider and the four-way wideband filtering power divider are designed and fabricated.The proposed topology achieves good isolation for the multi-way power dividers.3.A novel topology of dual-band filtering power divider is proposed.Continuing the design method proposed in this dissertation,the dual-band power dividers with good filtering characteristics and good isolation are proposed by combing the dual-mode dual-band resonators and the proposed isolation network.Through appropriate design changes in the proposed isolation network,two different isolation designs are implemented to meet the different requirements of the dual-band power dividers.One is to achieve good in-band isolation in both two passbands of the dual-band power divider;the other one is a very wide isolation band that could cover the two passbands of the dual-band power divider.4.A wideband filtering power divider with good isolation enhanced by a hybrid Wilkinson and Gysel topology is proposed.Gysel power divider is another kind of typical power-dividing topology.It is found that by combining the isolation networks of Gysel and Wilkinson power dividers,the bandwidth of the isolation band could also be extended.Based on this topology,the additional coupled lines are installed at the ports to improve the passband bandwidth and filtering characteristics of the proposed power divider.Finally,a good in-band and out-of-band isolation is achieved in the proposed wideband filtering power divider.5.Research on how to ensure good isolation in wideband unequal filtering power divider is emphasized.Regarding the problem that it is not easy to realize the good isolation in unequal power division,a novel compact wideband filtering power divider with modified isolation network is proposed,which could achieve a wide isolation band in the unequal wideband filtering power divider.