Research On Microwave/Millimeter-Wave Power Synthesis Circuit

With the rapid development of microwave/millimeter-wave wireless communication system,the demand for power combiners with miniaturization,multiway,high efficiency and high isolation is constantly increasing.This thesis focuses on the research of high-performance power combining circuit and based on the characteristics of various transmission lines,several multi-way power combiners with new structures have been proposed.The main research contents of this thesis include the following:1.Based on the basic theory of radial multi-way power combining,three multi-way radial waveguide power combiners with high isolation have been proposed.Firstly,the impedance matching and mode transformation in the radial waveguide are realized by voltage and current probes,and the isolation circuit is built between the output ports according to the implementation principle of Wilkinson power divider.An eight-way radial waveguide power divider with high isolation has been designed.Secondly,an improvement is made on the eight-way radial waveguide power divider.The power divider waveguide cavity which realizes eight-way radial power distribution and the isolation waveguide cavity with microstrip isolation circuit are combined to reduce the difficulty of fabrication and assembly of the device.Finally,a compact high-power four-way combiner based on single ridged waveguide has been designed by using the feature that ridged waveguide can reduce the cross sectional dimensions of waveguide.By reasonably designing the dimension parameters of the transmission structure of the ridged waveguide,the transverse dimension of the device can be limited to one wavelength while ensuring the power capacity to meet the requirement.2.Using the feature of single end grounding of isolation resistor in Gysel power divider,the resistance-free isolation of power divider has been explored and a design method of multi-way resistance-free power divider with high isolation based on substrate matching load has been proposed.Firstly,based on rectangular waveguide-substrate integrated waveguide(SIW)vertical transition structure,two kinds of substrate matched loads realized by microstrip line dissipation structure and SIW resonator have been designed.Secondly,combined with Gysel power divider circuit topology,a four-way Gysel waveguide power divider with high isolation for millimeter wave band has been proposed.Finally,an improvement is made on the four-way Gysel waveguide power divider.Using the ridged waveguide-rectangular waveguide transform section,the size of the common waveguide cavity is reduced,and the isolation bandwidth of the power divider is increased,and the amount of the branches of power combiner is extended from four to six.