| Summary: | 碩士 === 國立臺北科技大學 === 電子工程系 === 106 === In this thesis, the design method of multifunctional microwave Baluns are presented. The first balun can realize dual-band, impedance transformation and high isolation. The second balun can realize wide-band and complex impedance transformation. The first Balun structure mainly consists of Wilkinson power divider, by replacing two of /4 transmission lines with ＋90/90 step-impedance-stub lines and 90/＋90 T-shaped coupled line can realize dual-band differential output characteristics. However, adding another /4 line behind port1 to realize impedance-transformation and a resistor between port2 and port3 to realize high isolation. The second Balun structure is design of a branch-line coupler which open the isolation port and applying even- and odd-mode analysis to achieve characteristics of Balun. For using double-stubs coupled line to realize wide-band. And adding a resistor at mid of coupled line is the point to realize complex impedance-transformed and high isolation. According to the test results, two of the multifunctional microwave Baluns is fabricated and measured. The measured S-parameters and phase difference are consistent with the simulation result, which validates the proposed design is feasible and useful.
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