Study And Application Of The Periodic Structure In High Power Millimeter Wave

In recent years,with the continuous development of science and technology,millimeter wave technology has shown broad application prospects in the military field and civil fields.The periodic structure,which is an important design structure of millimeter wave devices,has attracted more and more researcher's attention.Reflective or transmissive devices based on periodic structures,such as planar reflective array antennas,frequency selective surfaces,couplers,polarizers,and beam splitters,are suitable for millimeter wave applications,because of the characteristics of easy processing,low cost,small size,and easy integrating.At the same time,the analysis and calculation of the periodic structure device need only be applied to one periodic unit in the device.Through designing and repeated iterations of the periodic cell structure,the ideal cell structure is quickly optimized,which can greatly improve the design efficiency and performance of the overall device.At present,gyrotrons with high power output characteristics are usually used as millimeter wave system sources in millimeter wave transmission systems.In order to avoid problems such as electrical breakdown during device operation,transmission devices with high power capacity need to be designed,and the periodic structure with many of characteristics is an effective way to solve such problems.Therefore,it is of great engineering significance to research high-power millimeter-wave devices based on periodic structures and tap their potential applications.This paper mainly studies the reflective circular polarizer,reflective diffracting beam splitter and anomalous reflector based on periodic structure that can be applied to high-power millimeter wave transmission systems.The main work of this paper are as follows:Firstly,the thesis expounds the theory of grating circular polarizer and the theory of electromagnetic diffraction of grating.On this basis,the grating circular polarizers of various contour units such as rectangle and ellipse are designed.In order to broaden the axial bandwidth of the device,a mushroom-shaped periodic structure is used to design a reflective grating circular polarizer,which has the characteristics of high power capacity and wide axial bandwidth.Through the physical processing and test analysis of the device,the theoretical design results of the grating circular polarizer can be well verified.Secondly,based on the vector diffraction theory of the grating,this thesis designs the two-way diffractive beam power splitter based on the U-shaped and double-sinusoidal periodic structure,and compares the performance of the two designs.After that,on the basis of the dual sinusoidal grating two-way power splitter with a wider band,this paper designed a three-way diffractive beam power splitter,and simulated the two designs in FEKO software.The simulation results show that these devices can achieve equal power radiation of different diffraction orders and have good working bandwidth,which verifies the effectiveness of the design.Thirdly,the paper introduces a metatagrating device based on periodic structure,and elaborate on the working principle of metatagrating as anomalous reflector.On this basis,a new type of metagrating based on PCB technology is designed.This design can achieve high-efficiency abnormal reflection in a wide frequency band.