Design And Development Of Limiter Based On High Temperature Superconducting Material

An important part of radar systems,electronic countermeasures systems,and communication systems is the reception of signals.But in the receiver system,it often occurs that the receiving equipment is saturated or even burned due to its own reasons or the input of external high-power signals.Therefore it is necessary to add a limiter in its front end.When a low-power signal is received,the signal can be passed without loss;and when faced with high power signals,the signal will have a large loss.The stronger the signal,the greater the loss.The conventional limiter will be faced with the bandwidth,withstand power,response time,loss and other key technical indicators between the constraints of each other,it is difficult to achieve fully satisfactory performance,resulting in serious limitations in the development of the receiving system,so the research task of a new generation of microwave limiters with lower loss,greater withstand power range,wider bandwidth is imminent.Since the first discovery of superconductivity in 1911 and the discovery of the high-temperature superconducting material yttrium barium copper oxygen in 1987,experts from all over the world have begun to carry out extensive research on superconducting materials,and the high-temperature superconducting materials discovered in the research are unique.The characteristics of superconducting devices further promote the development of new superconducting devices.The high-temperature superconducting limiter studied in this paper works is based on the extremely low surface resistance and critical current density of high-temperature superconducting thin films.The extremely low surface resistance of the high temperature superconducting film results in a very low insertion loss of the high temperature superconducting limiter,which greatly reduces the impact on the sensitivity of the receiver system.At the same time,when the current density inside the limiter is lower than the critical current density value of superconductivity,the limiter is in a very low loss superconducting state;when the current density exceeds the critical current density value of superconductivity,the limiter loses its superconductivity and transforms into a high loss normal state.The core work of this paper is to analyze the nonlinear characteristics of superconducting thin film materials,take advantage of the extremely low surface resistance and critical current density（J_c）characteristics of superconducting thin film materials,and combine the relevant theory of high temperature superconducting limiters.The design of the high temperature superconducting limiter is realized by electromagnetic simulation software,and finally the manufacturing and testing of the limiter are carried out.In this paper,the microstrip line structure is used to simulate the design of the limiter,and the superconducting limiter with operating frequency of 3 MHz-6 GHz is realized.The surface waveguide structure realizes the design and simulation of the superconducting limiter whose operating frequency is from 3MHz to 18 GHz.In the design process,the impedance matching between the limiter section and the 50Ωinput and output ports is realized by using the impedance transformation structure.The simulation optimization is carried out,and the size of the limiter structure is finally determined by analyzing the return loss and current density parameters of the limiter,and the design and simulation of two superconducting limiters that meet the design requirements are completed.The high-temperature superconducting limiter is fabricated using the semiconductor planar processing technology,including the preparation of high-temperature superconducting thin films,photolithography of superconducting circuits,etching of gold layers,and cutting of superconducting circuits.The high-temperature superconducting limiter is tested and analyzed for its limiter performance in a stable vacuum and low temperature environment.