Reseach On Stealth And Electromagnetic Protection Technology Based On New-type Electromagnetic Structure

As the development of electromagnetic(EM)detecting technology and EM weapons,stealth technology and defending for high intensity EM wave become more and more important in modern battlefield.Advanced stealth technology and effective means of protection for high intensity EM wave can improve penetration ability of fighter and survivability of information equipments.In this work,three kinds of miniaturized absorptive/transmissive radomes are designed in order to meet the requirement of stealthy and communication.This paper also studies the optimal design methods of energy selective surface(ESS)and limiting frequency selective surface(ESS),aimed at solving the requirement of defending for high intensity EM wave.The protection mechanism and design procedures of 3D protection structure also are researched.In addition,a miniaturized absorptive/transmissive radome with switchable passband and wide absorbing band is designed.The main research results in this work are as follows:1.Two miniaturized absorptive/transmissive radomes are designed based on the lumped loading technique and interdigital square loops.The relationship between insertion loss and gap between resonant frequencies of passband layer and starting frequency of absorbing band is studied by analysis of common equivalent circuit of absorptive/transmissive radome.The influence of thickness and permittivity of dielectric layer to starting frequency of absorbing band is also researched.The equal period of resistive and passband layers shorten the simulated time effectively.At same time,the designed radome has wide absorbing band and well angle stability.2.A absorptive/transmissive radome with two passband is designed.The structure with two passband closely spaced is designed using lumped loading technique.The absorptive/transmissive radome with two passband is designed after optimizing the structural parameters of resistive layer.In addition,the radome not only maintains angular stability,but also has wide absorbing band.3.The optimum design procedures of ESS and limiting FSS are studied.In order to guarantee the consistency of simulation and measurement,the transmission coefficient of nonlinear devices is measured firstly and the parameters of its equivalent circuit are obtained by fitting the transmission coefficients of measured to that of equivalent circuit of nonlinear devices.Then the unit cell of ESS and limiting FSS are optimized.The simulated results show that the optimized structure has lower insertion loss and same shielding effectiveness.4.A miniaturized absorptive/transmissive radome with switchable passband and wide absorbing band is designed.This work analyzes the influence of structural parameters to transmission and absorbing performance of radome detailedly.The designed radome not only has wide absorbing band and well angle stability,but also switchable passband which can be triggered by incident wave directly.5.A 3D protective structure with wide working band is designed.Firstly,the operating principle of the structure is studied from the perspective of equivalent circuit and equivalent medium parameters.The influence of structural parameters on the passband is analyzed.Compared to traditional 2D self-activated structure,the designed 3D structure possesses wider working band and smaller fluctuation in pass band.