The Research Of Ku-band Broadband Fast Beam Switch

This paper focuses on the research of Ku band broadband fast beam switch.Ku-band broadband fast beam switching switch is based on four-port differential phase-shift circulator,which has larger power capacity and is mainly used in high-power microwave systems.Based on the principle of Ku-band broadband fast beam switching switch,the structure of high-power beam switching switch is constructed on the basis of the analysis of Magic T,Pi/2 differential phase shifter and 3dB narrow-edge crack bridge which constitute Ku-band broadband fast beam switching switch.In order to satisfy the requirement that the bandwidth of the beam switching switch is more than 1.5GHz in Ku band,Magic T and 3dB narrow-edge crack bridges are designed and optimized based on the principle of multi-stage matching.The design results of the two bridges with echo loss less than-20 dB,transmission loss-3dB and bandwidth of about 2.5GHz at each port are obtained.It shows that the bandwidth of these microwave components can be effectively broadened by using multi-stage matching structure.To solve the problems of power,heat dissipation and external magnetic circuit structure,the design and optimization of the ?/2 differential phase shifter are carried out by using H-plane unilateral loaded ferrite sheet structure.The results show that in the frequency range of 13.0GHz~15.2GHz,the return loss of the port is less than-20 dB,the insertion loss is-0.06dB~-0.02 dB,and the differential phase shifts are 90° ±10°,and the performance of the pi/2 differential phase shifter is good.On this basis,the overall performance of the Ku band broadband fast beam switching switch is designed and simulated.The results show that in the range of 13.2 GHz to 14.8 GHz,the port reflection is less than-20 dB,the insertion loss is less than-0.07 dB,and the bandwidth is 1.6 GHz,which meets the design requirements of broadband and low insertion loss.The function of the beam switching switch is realized by changing the applied magnetic field.In order to solve the heat dissipation problem under high power,the Ku band broadband fast beam switching switch is analyzed by using ANSYS steady-state thermal simulation tool Steady-State Thermal under the condition of 1.5kW average power.According to the thermal analysis results,the steady-state thermal simulation of insertion loss-0.07 dB and-0.7 dB in the simulation results are carried out respectively.The results show that when insertion loss is-0.07 dB,the maximum temperature is 71.7? under air-cooled condition;when insertion loss is-0.7 dB,the maximum temperature is 485.7? under air-cooled condition;and when insertion loss is-0.7 dB,the maximum temperature is 100.1? under water-cooled condition.Ku-band broadband fast beam switching switch needs external drive circuit system to realize the function of beam switching switch.According to the driving system principle of Ku band broadband beam switching switch,the excitation circuit of H bridge of NMOS transistor is designed.The circuit schematic diagram is designed by using Altium Designer software,and the physical design and test are carried out.The logic control circuit is designed and simulated by using Verilog HDL hardware programming language,and the function and test of the logic control circuit are realized by using Xilinx development board.The preliminary design of the external magnetic circuit model was carried out,and the switching time was predicted by using MATLAB.The result was 0.4ms.The driving circuit system designed in this paper can realize the voltage range,current direction switching and pulse width adjustment of the driving end from 0 to 50 V.The current tolerance is 60 A,the internal resistance is about 0.6 m under complete conduction,and the fastest switching frequency is 600 kHz.It has good logic level compatibility.It is a driving circuit suitable for most ferrite beam switches and phase shifters.It has high versatility.