| Summary: | 碩士 === 國立臺北科技大學 === 電子工程系研究所 === 103 === This thesis proposes a novel reconfigurable impedance matching network, called self-tuning impedance matcher (STIM). STIM aims at the application of in-vehicle digital audio broadcasting (170−240 MHz). The purpose of STIM is twofold. Firstly, under the high-speed vehicular environments, DAB antennas may have frequency detuning effects, thereby leading to a lower reliability. In this case, STIM is capable to adapt the DAB antenna to the changes of its environment, retuning the antenna to its operational frequency. On the other hand, STIM can make other antennas originally for digital television (DTV, 470–894 MHz) and FM radio (136–174 MHz) operate in the targeted frequency band, thereby lowering the setup cost of DAB devices. The STIM template has the configuration of non-uniform microstrip lines, using relay switches as the reconfigurable mechanisms. The various widths of the microstrip line are determined by solving the mathematical programming problems. As a result, STIM can turn a DTV antenna and an FM antenna into a DAB antenna, respectively. The impedance bandwidth of a state is 20 MHz, under the criterion of VSWR &;lt; 2. Meanwhile, the transducer gains are larger than –4.16 dB. Once the matching criterion is relaxed to VSWR &;lt; 2.5, the impedance bandwidth of a state is 30 MHz, and the transducer gains are larger than –3.14 dB. Simulated and measured results are presented to demonstrate the validity of STIM.
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