| Filter is the kernel of many design problems in wireless technology. The development of modern communication technology encounters many new and special requirements such as low-coupled, wideband, high-speed adjustability and large power capacity. Meanwhile, plasma microwave devices become new research interests owing to their small, light and powerful characteristics.This thesis is based on modern microwave filter design theory. Considering the basic electromagnetic characteristics of plasma, the sandwich structure non-magnetized plasma rectangular waveguide filter is investigated in detail theoretically. Firstly, the distribution of electromagnetic field in the plasma filter is studied. The transmission coefficient is calculated and the completely transmission phenomenon under plasma frequency is observed and verified. Resonance of the filter is approved based on power calculation. Furthermore, new concepts of equivalent PEC wall and equivalent microwave resonance cavity are suggested to analyze the resonance phenomenon and filtering effect. The relationship between the filter structure and the filter center frequency is acquired and a method to calculate this center frequency is proposed. Based on theoretical analysis, several plasma filters working in S and C band are designed using electromagnetic simulation software and the electrical tunability of the plasma filter is studied carefully. In the end, An experimental plan to implement plasma filter is suggested. The vacuum system and spectrum analysis system used in the experiment are designed to complete the preparation process of the plan. |
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