Research On The Design Of Energy Selective Electromagnetic Protection Structures And Component For The RF Front-end

With the rapid development of electromagnetic attack technology,electronic equipment is facing an increasingly severe threat.It is urgent and significant to study electromagnetic protection(EP)technology to ensure the survival and effective performance under electromagnetic attacks.Compared with the energy coupling channels of non-working signals such as holes and cables,the RF front-end is the weakest link under electromagnetic attacks,and it is also a major difficulty in EP technology research.Among the EP technologies applicable to the RF front-end,the energy-selective electromagnetic protection(ES-EP)technology has gradually become a research hotspot due to its advantages of being "capable,compatible,and controllable".However,there are still many problems to be solved in the research of ES-EP technology in terms of theory and measurement,indicators and engineering,and application scenarios and form.This paper mainly focuses on the restricting scientific problems during the engineering of ES-EP technology,and researches the design of ES-EP structures and components.The main work is as follows:(1)Systematically concluded the threats,damage mechanisms,and coupling channels of electromagnetic attack faced by electronic equipment,and then defined and classified EP methods from the aspects of coupling methods and protection dimensions.Power limiters,phase-change materials,frequency selective surface,and other RF frontend EP technologies are illustrated.The progress of ES-EP technology is mainly reviewed,and the advantages and disadvantages of the aforementioned technologies are compared,which lays the foundation for the follow-up research in this paper.(2)To complete the theoretical system of ES-EP,the concept and mechanism of the energy-selective mechanism(ESM),as well as the indicators such as protection threshold,insertion loss,response time,and operating bandwidth,are defined in detail;starting from the energy-selective induction circuit,the microwave response process of the ESM are expounded.In terms of test methods,a quasi-TEM waveguide test based on the theory of artificial magnetic conductors(AMC)is proposed to solve the contradiction between the cost and accuracy existing in methods like space illumination and rectangular waveguide.Uniform electromagnetic field distribution is realized in the waveguide by loading a highimpedance surface(HIS)array in the rectangular waveguide,thereby combining cost and accuracy.The simulation and measurement results show that in more than 90% of the transverse area in the proposed quasi-TEM waveguide,the variation of the electric field intensity is less than 1d B,which can be used for high-precision testing of the fieldinduced structures and components such as energy-selective surfaces(ESS)at low cost.(3)In the protection of space transmission,the electronically scanned antenna/array(ESA)used in the radar system is adopted as the protection object.According to the spectrum of electromagnetic attacks,the low-pass and band-pass ESSs are designed.Then the transient responses of the ESSs under three typical strong electromagnetic attacks are compared and analyzed to verify the protection performance.Then,the energy selective electromagnetic protection radome(ES-EPR)is designed for the antenna,and its influence on the radiation performance and improvement of protection performance under electromagnetic attack is evaluated.The results show that the ES-EPR can provide protection effectiveness of not less than 25 d B with the radiation pattern remaining unchanged and the gain-loss less than 0.5d B.In addition,aiming at the bottleneck limitation to control the thermal loss,the electrothermal coupling simulation is utilized to optimize the design of the ES-EPR.At the maximum steady-state temperature bellowing150 °C,the transmit power of the unit antenna can reach 30 W,and withstand electromagnetic attack by 200 k V/m.(4)In the protection of field-circuit conversion,a planar reflectarray antenna(PRA)based on the reflective ES-EP structure is proposed to meet the EP need of the reflector antenna that has no selectivity high-gain for working signals and strong electromagnetic signals.The reflective ES-EP unit is designed according to Huygens’ principle and generalized Snell’s theorem with gradient phase and energy-selective characteristics,enabling the PRA to adaptively defocus and reduce gain,thereby alleviating the received power to confront strong electromagnetic attacks.Therefore,the problems of the large surface area and structural conformality of the ES-EPR are avoided.The simulation and measurement results show that the designed PRA can form a high-gain beam of 25 d Bi,and provide protection effectiveness of no less than 20 d B for the RF front-end under high repetition frequency,wide pulse width electromagnetic attack.(5)In the protection of transmission lines,ES-EP waveguide components are proposed in view of the key constraints such as large peak leakage and small power capacity.Among them,the filter-type ES-EP component switches the passband through the movement of the forbidden band of the active HIS,which suppressed the transmission of surface waves and reduces the transmitted power.The absorbing-type ES-EP component realizes the absorption of electromagnetic signal energy through the resistance characteristic of the induction circuit,which reduced the energy of reflected and transmitted waves simultaneously,thus realizing EP for microwave switches,multiplexers,and others.According to simulation and measurement verification,the insertion loss of the filter-type EP waveguide component is less than 1d B,and it can provide a protection capability of no less than 10 d B within 20% of the bandwidth,and there is no peak leakage;the absorbing-type EP waveguide component has an insertion loss of less than 1d B,the absorption rate is higher than 90% in the band from 10.5GHz to 12.5GHz,and the power capacity to the continuous wave is no less than 20 W.