Research On E-band Millimeter Wave Multiplexers

As an important component of RF communication system,multiplexer is widely used in modern wireless system,radar system,satellite communication and laboratory measuring equipment.As the research field of wireless communication focuses towards on higher frequency bands,the current spectrum resources have become more and more valuable.In order to reduce the complexity and sampling rate of baseband digital processing effectively,achieve faster digital transmission rate and and long-distance wireless communication,in millimeter wave E-band a multi-subband communication system is designed.Different from the traditional E-band FDD communication system,in this paper the main function of the E-band multiplexer is designed to divide the broadband signal received by antenna into multiple subbands.The spacing between the subbands is very narrow,which requires higher isolation degree of multiplexer.Multiple subband signals transmit single data stream in parallel separately.Therefore,it is very necessary to adopt a multiplexer with good frequency response and high subband channel isolation degree in order to improve the communication quality.In this paper,the design of millimeter wave multiplexer mainly includes two parts,the first is the design of the filter.Based on filter theoretical basis and the design principle of waveguide filter,this paper introduces the design methods of metal diaphragm and iris waveguide filter by direct coupling modes,and then the design methods of dual-mode waveguide filter are further studied for the sake of exploring the reliable design of waveguide devices miniaturization.The second is the design of the matching structure of each channel.This paper uses the structure of adding slots in the T-junction to complete the matching design of each passband filter.Firstly,this paper illustrates the design method of traditional band-pass filter,and describes in detail the general steps of synthesizing the E-plane metal insert band-pass filter design by using the resonator coupling coefficient and the external port group delay.Based on the co-optimization simulation of electromagnetic and circuit,the precise designs of the diplexer and multiplexer of the E-band metal diaphragm structure are given.Iris filter is a classical waveguide filter structure.This structure has advantages as low insertion loss,high isolation degree and large power capacity.In this paper,the electromagnetic simulation of E-band iris waveguide diplexer and multiplexer is realized,and the waveguide diplexer is fabricated.The measurement results show that the bandwidth and the isolation degree between channels of the diplexer are in line with the design indexes,it can guarantee the good transmission quality in E-band.Due to the influence of machining error,the frequency shifts 550 MHz to the low frequency band,which is less than 0.5% of the center frequency.After size compensation for the design size,the simulation results are basically consistent with the actual measurement results.At last,the structure of two-mode waveguide diplexer is introduced,which is very suitable for the design of excellent performance millimeter-wave diplexers because of its rapid simulation and optimization,and its ability to generate transmission zeros and shorten the volume of the waveguide devices.The actual measurement results show that the simulation results of the diplexer accord with the theoretical response.In this paper,the simulation and implementation of E-band millimeter wave diplexers and multiplexers provide practical experience reference for the subsequent related research.