On The Relationship Between Structure Parameters And The Electric Performance For Bandpass Filters

This thesis has been done with the scientific research projects. The work can been divided into two parts: The content of the first part is on the relationship between structure parameters and the electric performance for wave-guide bandpass filter and coaxial tunable filter. The content of the second part is to fabricate the engineering prototype of double-patterns four-arm plane spiral antenna.Firstly, in the research of the relationship between structure parameters and the electric performance for wave-guide bandpass filter and coaxial tunable filter, the relationship between structure distortion on the surface of wave-guide and the electric performance has been analyzed. The geometry theory model of structure distortion on the surface of wave-guide has been founded and analyzed by HFSS. According to the analyzing data, the curve of the relationship between structure distortion on the surface of wave-guide and the electric performance has been simulated by MATLAB.Secondly, a lot of literatures have been refered and studied, and the institute engineering experience has been combined. The design method of equivalent circuit for filter has been adopted. It has been discussed deeply with institute engineering personnels and we have confirmed the key structure parameters which affect the electric performance of wave-guide bandpass filter and coaxial tunable filter together. And the research between electromagnetic subject and mechanism structure subject is analyzed. Based on the analyzing researches, the relationship expression between structure parameters and the electric performance for wave-guide bandpass filter and coaxial tunable filter has been given.At last, in order to validate the relationship expression between structure parameters and the electric performance for wave-guide bandpass filter and coaxial tunable filter, HFSS and the relationship expression to analyze the electric performance of special filter is adopted. The analyzing results are compared and if two methods agree well, it will verify the correctness of the relationship expression given in the thesis. Therefore, it designs wave-guide bandpass filter and coaxial tunable filter of good electric performance in the thesis and makes them as studying object.The second research of the thesis is to design a double-patterns four-arm plane spiral antenna with the background of wideband circular polarization plane antenna's technology. It uses HFSS to analyze and simulate the antenna. The analyzing results indicate that the antenna's VSWR is less than 2 and the axial ratio is less than 3 dB in the working band form 3 to 12 GHz. According to the results, the engineering prototype of antenna is fabricated and the feasibility of actualizing the electric performance of antenna's double-patterns is verified.