| In the microwave, millimeter-wave systems, the waveguide filter is widely used for its high Q value, low loss, high power capacity and large selectivity coefficient. Conventional waveguide filters are generally implemented by the method of direct-coupled cavities, which can realize a high selectivity, but the larger size and more complex manufactures are inevitable. In order to overcome these shortcomings, we conduct this research on the novel waveguide filters, which are designed with small size and high performances.First, a compact E-plane waveguide filter is designed and analyzed base on the traditional metal septa E-plane waveguide filter. The overall length of the proposed waveguide filter is less than a half waveguide wavelength. This filter design idea is to bring in two transmission zeroes by adding an extra resonant cell between the two metal septa, which will contribute to improve the selectivity. We also fabricate the novel compact E-plane waveguide filter, and the experiment results agree well with the simulation results.Secondly, a novel waveguide filter called EIT waveguide filters is designed, which based on the Electromagnetic Induced Transparency(EIT) effect. The presented EIT waveguide filters have a very small size with less than 3 mm and is a more compact waveguide filter than the proposed one in chapter 2. The basic idea is to bring bright mode and dark mode in the standard rectangular waveguide, and then a transparency is brought in the original stopband by the interaction between the dark mode and the bright mode. The transparency passband will fulfill our demand by reasonable design. We design two type structures based on this design method. Numerical simulations are implemented and experimental samples are fabricated in the chapter 3. The measurement results are in good consistency with the simulation ones.Thirdly, a novel low-pass filter with large rejection is designed. A compact cavity resonator cell structure named compact SRR resonance unit is proposed. By designing the resonance unit length dimension, the number and orientation of the resonance units, the novel lowpass filter with high rejection level in the entire W-band can be implemented, which perhaps improve the isolations between the different ports of the active opponents, such as mixers.Finally, based on the novel waveguide filters designed in this paper, their applications are researched, for instance a novel duplexer and a broadband mixer are designed and fabricated. The experiments have good consistency with simulations.In short, in this thesis, not only the novel waveguide filters have been designed and fabricated, but also their possible application researches have been conducted. The research works will provide a theoretical and practical significance. |
