Research On Beam Splitting Technology And Polarization Control Technology Of High-Power Grating

With the rapid development of high-power microwave technology,the output power of microwave sources and application systems has been continuously improved,and the problem of insufficient power capacity of transmission and feeding devices has become increasingly prominent.From the perspective of new structure and new mechanism,it is urgent to seek to solve the power capacity problem of typical devices such as power dividers and polarizers in feeder links.Compared with waveguide devices,quasi-optical devices have innate power capacity advantages due to the large cross-sectional area of the transmission channel and the ease of single-mode control.This thesis focuses on the HPM grating beam splitting（power splitter）and polarization（polarizer）control technology,and explores the technical approach to realize high power capacity co-polarized power splitting and arbitrary polarization control by using the quasi-optical method.The specific research contents are as follows:1.Research on high power capacity grating beam splitting technology.The main contents include:（1）A new asymmetric TM wave co-polar transmission grating beam splitter is proposed,its relative bandwidth can reach more than 16.7%under the condition of power division unbalance±1%,and the power capacity can reach 5.94 GW,the incident angle tolerance at frequency point f₁ and frequency point f₂ can reach more than 12°under the condition of power division unbalance±1%,which improves the beam splitting performance of the grating under weak collimation conditions;（2）Around In-depth theoretical and experimental studies have been carried out on the high power capacity index of grating.The calculation formula of the grating power capacity under Gaussian beam irradiation is theoretically derived,which lays a foundation for the application of high-power grating beam splitters in practical engineering design.In addition,in order to solve the engineering technical problem of examining the withstand power index of the grating beam splitter under the existing power level of about 5 GW,the electric field strength at the grating cannot reach the breakdown threshold in the experiment,and a cross-waveguide type quasi-optical power threshold is proposed.The test system can better solve the technical contradiction between maintaining the quasi-light environment of the grating and increasing the electric field strength at the grating as much as possible in the experiment.The tests of grating power capacity and grating beam splitting efficiency were completed when the electric field strength was 500 k V/cm.2.The research on dual grating arbitrary polarization output technology is carried out.（1）The theoretical study of the dual-grating polarization arbitrary control technology was completed,and the orthogonal mode transmission characteristic matrix of the plane electromagnetic wave under the double-grating reflection case was deduced.（2）The design and optimization of a 45°oblique-incidence dual grating polarization rotation system was completed in combination with the engineering needs of the project,and a solution to meet the requirements of continuous control of the polarization angle was given.Double grating rotation angle optimization adjustment curve.The simulation results show that the use of this technical solution can realize the adjustment of any polarization mode of the output beam,and the polarization purity is more than 95%.