Study Of W-band Mixer

In modern communicationg systems, mixer is always used as the first component. The performance of the whole system is affected by the performance of the mixer. So mixer becomes one of the important components needed to design. The studies on a single balanced mixer and a harmonic mixer are proposed in this thesis..In this thesis, the historical development and future trend of millimeter-wave mixer are introduced at home and abroad firstly. It also introduces several different types of mixer and the advantages and disadvantages of using them. Meanwhile, the conceptions of the mixer's index are given. The method of analysing mixer (harmonic balance and transpositional matrix) is also introduced.Based on the above dicussion, the thesis mainly focuses on two different kinds of millimeter mixers: a W band single balanced mixer and a W band eighth sub-harmonic mixer. In the design of W-band balanced mixer, the energy of RF and LO (transmitted to the circuit by Waveguide-to-Finline Transitions) is transmitted to diodes by hybrid ring which is made on a planar circuit. The gold wire is used to connect two branches and the generated signal is transmitted to port by a section of high impedance line; And in the design of eighth sub-harmonic mixer, we use DMK2308 made in Alpha Industry as the antiparallel diode pair. The circuit structure is made up of Waveguide-to-Microstrip Probe Transition, LPF and matching circuits. Based on the results of the theory analysis and computer simulation, the structures were designed and manufactures were made. Finally, the indexs of these mixers were measured.Improvement of the mixer is introduced in the end of the thesis based on the results mesured. The result discussed above is not satisfied of this integrated construction, more research effort is required next. As a key component of receiving system, mixer plays an important role and improves the performance of all systems directly. The study on mixer is meaningful.