Research On Ka-band High-isolation Waveguide Power Dividers/Combiners

Since the birth of radio, there has been a very rapid growth of radiocommunication. Toobtain higher information transmission rates over larger distances, there has been a steadydemand for using higher frequency bands and larger amounts of transmitted power. So far,output power from single solid-state device is not enough, which can not meet therequirement of high power applications. To obtain high power level, power from multipledevices is combined. Power divider/combiner is the key component, which affects theperformance of the system. Thus, there has been growing interest in develop different kinds ofpower dividers/combiners.Power dividers/combiners are widely used and amplitude balance and phase balance arerequired for power-combining amplifiers. Besides, the isolation characteristic of powerdivider is also very important, which promises the independence of different output ports.This thesis will focus on high-isolation waveguide-based power dividers/combiners and themajor achievements are listed as followed:1．A waveguide magic-T based on waveguide-to-microstrip transition is proposed, whichhas coplanar arms. The four arms of the waveguide magic-T are placed in the same plane byutilizing waveguide-to-microstrip transition. For the traditional matching elements, like cones,wedges, pins and irises are not needed, the proposed magic-T features easy connection,fabrication and assembly. The principle and derivations of S-parameters are introduced in thisthesis. Then, the design procedure is described in detail. At last, a Ka-band E-planewaveguide magic-T with coplanar arms is designed, fabricated and measured, which validatesthe proposed structure.2. A waveguide magic-T based on ridge-waveguide couplers is proposed, which hascoplanar arms. The ridge-waveguide coupler has lower insertion loss and higher powercapacity with regards to waveguide-to-microstrip transition. The principle and designprocedure are described in detail. At last, a Ka-band E-plane waveguide magic-T withcoplanar arms which is based on ridge-waveguide couplers is designed and full-wavesimulations are carried out. 3. A microstrip dual-probe power divider/combiner based on TE20mode is proposed. Theisolation characteristic is improved with regards to the traditional microstrip dual-probestructure. Then, a TE20mode waveguide-based branch line coupler is designed. At last, theyare cascaded to form a multi way power divider.