Research And Application Of Artificial Magnetic Conductor In Microwave And Millimeter Wave Devices

In recent years,as a new type of metamaterial,artificial magnetic conductor(AMC)has both inphase reflection characteristics for plane waves and electromagnetic bandgap characteristics of specific frequency bands,which can break through the limits of traditional microwave and millimeter wave device structure design and improve the overall performance of microwave and millimeter wave devices.The structure has the characteristics of simple structure and easy preparation.Gap waveguide(GW)is a new milliwave waveguide medium.This technology is based on parallel plate waveguides,loaded with a periodic AMC structure,and uses air as the propagation medium,which largely avoids the loss of dielectric materials.This article focuses on the application of ridge-gap waveguide technology in microwave and millimeter-wave passive devices.In this way,combining the advantages of microstrip lines to design millimeter-wave passive devices based on ridge-gap waveguides will have great practical value.The emergence of gap waveguides is inseparable from the development of the electromagnetic band gap structure,so this article firsty introduces the basic principles of the formation of artificial magnetic conductors,starting with the study of the basic characteristics of artificial magnetic conductors,and presents the electromagnetic band gap structure of artificial magnetic conductors.The analysis method of this paper discusses the influence of each structural parameter on the band gap characteristics and relative bandwidth of the artificial magnetic conductor,and from this,the artificial magnetic conductor of the required frequency band is designed.On this basis,a printed ridge gap waveguide with a center frequency of 30 GHz is designed.Subsequently,a third-order coupling filter with transmission zeros on the upper sideband and a third-order coupling filter with transmission zeros on the lower sideband is designed using printed ridge gap waveguides.In the filter passband,the insertion loss is less than 1d B,and the return loss is greater than 15 d B.It has the characteristics of good frequency selectivity and strong out-of-band capability.Then,based on the mushroom-like AMC structure and printed ridge gap waveguide proposed above,a crossover with a ring coupling structure is proposed.Compared with the traditional crossover,the crossover has a flat multi-layer structure,and has the advantages of simple structure,low profile,easy manufacture and easy integration with other systems.In addition,the use of the ridge gap waveguide structure can make up for the large loss of traditional waveguide and microstrip structure in the millimeter wave frequency band,and achieve the characteristics of low loss and good transmission performance.The simulation result shows that the millimeter wave frequency crossover is in the working frequency band,the insertion loss is less than 0.5d B,the return loss is greater than20 d B,and the isolation is greater than 20 d B.It has good transmission performance and dual-channel isolation characteristics.Finally,based on the previous work,using the branch line coupling structure,a multi-transmission pole,broadband crossover based on printed ridge gap waveguides is proposed.The crossover makes up for the relatively narrow bandwidth of the loop coupling structure proposed earlier,and can be applied to the ultra-wideband field.Using the branch structure crossover,it can be applied to the Butler matrix to realize the passive beam forming feed network.The simulation results show that the crossover of the branch structure is in the working frequency band,the insertion loss is less than 1d B,the isolation is greater than 20 d B,and the working bandwidth is 3.5GHz.