Design On W-Band High-Order Resonator Bandpass Filter

With the rapid development of communication technology,the demand for spectrum resources below 40 GHz in communication systems is gradually expanding.In order to reduce inter-system interference,the available spectrum resources will develop to higher frequency bands in the future,so the research on W-band electromagnetic devices is of great value.Bandpass filter is important for a communication system,and the design of band-pass filters in the low frequency band is relatively mature,while the design and manufacture of band-pass filters in the W-band still needs to be further researched.In order to make full use of the electromagnetic spectrum resources of W-band,this paper investigated the design method of W-band waveguide bandpass filter based on rectangular waveguide theory and filter theory,and used UV-LIGA process to achieve the manufacture of the filters,which meets the current demand for low-cost miniaturized microwave devices for communication systems.(1)In this thesis,the resonant cavity coupling circuit synthesis method is used to analyze the high-order mode resonant cavity coupling circuit,and we designed a high-order mode resonant cavity bandpass filter based on TE301 resonant mode,studied the effect of sizes of resonant cavities on the performance of the waveguide filter,and analyzed the effect of different materials and surface roughness on the insertion loss and return loss of the filter.The center frequency of the filter is 94 GHz,the pass band is 82GHz~106GHz,the-3d B fractional bandwidth(FBW)is 25.5%,and the maximum insertion loss is at 84 GHz with the value of-0.8d B.(2)In this thesis,a perturbative rectangular dual-mode resonant cavity is designed and the corresponding mode is analyzed.Then a third-order dual-frequency bandpass filter is designed using this dual-mode resonant cavity by resonant coupling theory and computational electromagnetics method.The center frequencies of the two bandpass bands are 90.3GHz and103.7GHz,respectively,and the corresponding maximum insertion losses are-0.8d B and-0.2d B,respectively.The maximum stopband suppression is 69 d B.(3)The preparation method of bandpass filter is explored.The UV-LIGA process is used to prepare the filter.Based on this process,the preparation accuracy and efficiency are optimized,and the batch rapid replication of the filter is realized.At the same time,the requirements of miniaturization and low cost of RF devices for communication systems are met.In this thesis,SU-8 2100 negative photoresist was used to construct the filter structures,and magnetron sputtering process was used to realize the metallization of the filter.After that,the filter size and surface roughness were characterized by laser confocal microscope,and the transmission performance of the two filters was tested by microwave test platform built with a Keysight N5224 A vector network analyzer and R&S ZC110 spread spectrum module.The test results were basically consistent with the simulation results.