Research Of A Uhf Microwave Diplexer

In recent years, with the rapid development of information technology, microwave communication frequency resources become increasingly narrow, therefore, the performance of the microwave filter also be increasely demanded. Small size, high selectivity, low insert loss and large attenuation out of band are becoming the key technical requirements of microwave filter .According to the requirements of Xi'an Space Star Technology Industrial (Group) Company, the composition and design technology of the microwave diplexer are analysised. The design method of the band-pass filter in microwave diplexer is studied. The coupling parameters and transmission zero extraction method of the Chebyshev filter.are discussed. The ultra-high frequency microwave diplexer 900MHZ based on generalized Chebyshev function model in order to improve the filter-band attenuation,using the selected frequency branch connector and the coaxial cavity structure to achieve its high isolation, low insertion loss and high power capacity.Based on the research, the microwave diplexer with the center frequencies of uplink and downlink channels are 830MHz and 875MHz, the relative bandwidth of the two channels are 1.2%, and 1.14%, insertion loss less than 1.6dB,pass-band suppression greater than 50dB, sending and receiving end of isolation is greater than 90dB and power more than 100W is generalized The diplexer is stimulated and optimized by using the 3D simulation software Ansoft HFSS. According to which, the amplitude-frequency curve of the band-pass filter and the public-side diplexer group delay curve of the diplexer are achieved. The actual structure size of the diplexer is got from the coupling parameters. The microwave diplexer is realized based on the coaxial resonant cavity of microwave. And finally the proposed diplexer is tested and optimized by using Aglient E8362B vector network analyzer Test results show that the development and optimization of microwave diplexer meet the design requirements .