【正文】 er is investigated. Frequency tunable function is realized by changing voltage on varactors. First, in this paper, the microstrip dualmode ring filter is pared to other types of filters, after that the dualmode ring filter is chosen to realized the tunable filter due to its advantages. Then the structure and the design theory of microstrip dualmode filter are introduced. On the basis of these, tunable function is realized by varators and the tunable bandpass filter is investigated. Then, the filter is simulated by EDA tools like ADS and IE3D. Through the analysis of simulation data, the effects of variable capacitance on the frequency characteristics of the filter are obtained. Based on these, the SMV1236074 is chosen to realized the variable capacitor. After that, the actual layout of the circuit is designed. At last, the microstrip tunable filter is fabricated and tested. Both simulation and experiment show that the new tunable filter has a good performance and the measurement is in good agreement with the simulation. Key words: bandpass filter, microstrip line, dualmode resonator, varactor, tunable filter III 目 錄 摘 要 ................................................................................................................................................. I ABSTRACT ...........................................................................................................................................II 第一章 緒論 ......................................................................................................................................... 1 ............................................................................................................... 1 ......................................................................................................................... 1 ......................................................................................................................... 2 第二章 微波濾波器的基礎(chǔ)知識(shí) ............................................................................................................. 3 的分類 ...................................................................................................................... 3 ............................................................................................................... 3 ............................................................................................................... 4 ................................................................................................. 4 標(biāo) ............................................................................................................... 7 ............................................................................................................... 9 ............................................................................................................. 10 ADS仿真軟件 ................................................................................................................ 10 Zeland IE3D仿真軟件 ..................................................................................................... 10 HP8270矢量網(wǎng)絡(luò)分析儀 ..................................................................................................11 ...................................................................................................................................11 第三章 微帶雙模濾波器 ..................................................................................................................... 12 .............................................................................................................................. 12 ....................................................................................................................... 13 ........................................................................................................................ 13 ........................................................................................................................ 14 種不同響應(yīng)的雙模濾波器 ............................................................................................ 16 .................................................................................................................................. 17 第四章 電可調(diào)雙模帶通濾波器設(shè)計(jì) .................................................................................................... 18 .................................................................................................. 18 .................................................................................................................... 18 .......................................................................................................... 20 ............................................................................................... 20 ................................................................................................................. 21 IE3D仿真分析 ............................................................................................................... 24 .................................................................................................................................. 28 第五章 濾波器的加工與測(cè)量 .............................................................................................................. 29 .................................................................................................................... 29 ............................................................................................................. 29 .......................................................................................................... 30 ...................................................................................................... 31 ...............................................