Research And Design Of High Performance Microwave Multiplexer

The emergence and wide application of wireless communication systems have promoted the development of microwave devices.As the key components in wireless communication,the performance of filters directly affects the quality of the whole communication system.The compact resonator with low insertion loss,high selectivity and wide impedance band will become the trend of modern microwave filters design.With the development of society and the progress of communication technology,the spectrum resources available for wireless communication are becoming increasingly scarce.The research of multiplexers has attracted great attention in recent years.Since the widely investigated of high temperature superconducting(HTS)materials,researchers have found that HTS multiplexers have excellent performances,such as low insertion loss,sharp skirt selectivity and high level of isolation.Therefore,high temperature superconducting multiplexer has broad application in satellite communications,deep space exploration,national defense and military and other cutting-edge fields.In this paper,the proposed structure and design methodology of HTS filter and multiplexer are analyzed.The main contents of this paper are organized as follows:1.This article mainly introduces the design theories and methods of HTS filters and multiplexers.A single-port reflection group delay simulation method is introduced to design filters and multiplexers.2.A new type of hairpin resonator is proposed in this dissertate,the equivalent capacitance and inductance parameters are investigated to approach harmonic suppression.Dramatically compact structure of the resonator is realized by using fractal structure.Interpolation structure can effectively suppress the second harmonic.And a 5-order high temperature superconducting bandpass filter is designed and fabricated by using this resonator.3.The introduction of differential structure can effectively eliminate redundant admittance without extra resonators or structures to connect the channels.The occupied circuit of high temperature superconducting four-channel multiplexer is of compact size.And the circuit size is only about 20.5 mm 23.3 mm?.The simulation results show that the bandpass performance of each channel of the four-channel multiplexer is agree well with design specification,and the out-of-band suppression effect can reach 7 GHz.4.The concept and properties of multi-mode resonators are briefly introduced.The resonant characteristics of multi-mode resonators are analyzed by classical odd-even mode analysis method.The final specification of resonator is designed at 2.4GHz central frequency and the insertion loss is 0.73 dB.Meanwhile,the relative bandwidth of the 3dB of the multimode resonator is 30%.There is transmission zero on each side of the bandpass,which high selectivity of sideband is realized.Its 10 dB out-of-band suppression can reach 11 GHz,and has low insertion loss and compact circuit size.