Research On Key Technologies Of Multi-band High Power Microwave Feed System

With the development of multi-band high-power microwave technology,multiband radiation systems have become an important development direction for high power microwave antennas.Under the condition of maintaining high power capacity,using high power frequency selective surface(FSS)and dual band feed horn combination is a reliable technical scheme to realize the design of multi-band radiation system.The main work of this paper is to design several different types of FSS,S(2.3GHz)/C(4.3GHz)and Ku(12.5GHz)/Ka(31GHz)dual band feed horns.On this basis,a four band radiation system is designed.The research contents mainly include the following aspects:1.Multiband FSS researchAccording to the application requirements of S/C/Ka three band,the metal column is used as the three band cross-polarized FSS unit structure to transmit TE polarized microwave in Ka band and reflect TM polarized microwave in S/C band.The transmission and reflection efficiency of the simulation are more than 97%,the experimental results are good.The square hole with via structure is used as the co-polarized three band FSS unit structure to transmit Ka band TM polarized microwave and reflect arbitrarily polarized S/C band microwave.The transmission and reflection efficiency of the simulation are more than 95%,the experimental results are good.Ka band TE polarized wave can be transmitted by adding a side i-groove on the square hole FSS.The design of three band line or circular polarization FSS is completed.Ka-band circularly polarized wave has a transmittance of more than 95% at the center frequency of 31 GHz.According to the application requirements of S/C/Ku/Ka four band,the combined structure of cross hole slot patch and square ring is used as the four band FSS unit structure.At the same time,dielectric embedded technology is used to reduce the resonant frequency and improve the power capacity.Realizing linear polarization and circular polarization radiation of S/C/Ku/ka four wave microwave segment.The transmission efficiency at the central frequency point of Ku and Ka band reaches 92%.The power capacity reaches more than 0.15 GW in Ku/Ka band and 3GW in S/C band.2.Research on dual-band feed hornIn order to cooperate with the FSS array,S/C and Ku/Ka dual band horn feeds with changing flare angles are designed.The particle swarm algorithm combined with the pattern matching method is used to optimize the best variable opening angle structure of the horn.The S/C dual band horn is feed independently,with good radiation performance,reflectivity of the central frequency point is less than 5%,and good equalization performance within 3d B wave width.The Ku/Ka dual band horn feeds the same port due to the limitation of power capacity,with good radiation performance,reflectivity at the center frequency of the Ku/Ka band is less than 1%,and the equalization performance within the 3d B bandwidth is good.By adding a dielectric lens,microwave radiated from the horn port is similar to a plane wave.3.System simulationA four band radiation system is designed of near-field Cassegrain antenna,four band FSS array designed in this paper and tuo dual-band feed horn.The overall Simulation of the four band radiation system are completed and radiation characteristics of the four bands are good,with gains are greater than 27 dBi.