Research On Electromagnetic Properties Of Composite Structure With Thin Plasma Layer-Frequency Selective Surface

Stealth technology is the footstone of military equipments on battlefields.With the development of stealth technology and new materials,stealth structure is advancing towards wideband absorption,light weight,thin thickness and high strength.As a new kind of stealth technology,plasma stealth technology has its unique advantages over others,such as wider absorption bandwidth,better absorption effect and it can reduce air resistance as well.Compared with those simply absorption incident electromagnetic wave by plasma collision,the combination of plasma and Frequency Selective Surface(FSS)generates different novel composite structures.They can produce different electromagnetic transmission characteristics and realize flexible control of electromagnetic waves in different application backgrounds.This paper mainly focuses on the analysis and applications of the composite structure in field of frequency selection,shape stealth,absorption stealth,absorption/transmission radome and so on.Besides,different kinds of composite structure are designed to meet different requirements.The main work and innovations of the paper are summarized as follows:1.Propose a novel method of extracting equivalent circuit parameters by generic algorithm,and verify it by the patch type FSS and the square FSS in free space.The method has relatively high precision.Taken plasma as medium and loaded FSS structure made up of basic FSS units at both sides,the composite structure presents bilateral steepness electromagnetic characteristics.The transition between the rising and falling edges is within 0.2 GHz and out of band rejection is below-10 dB.Meanwhile,the operating frequency can be adjusted by changing the parameters of the plasma.2.Take plasma layer as research object and use the Maxwell theory,the boundary conditions and the transmission line model to calculate the absorption of incident electromagnetic waves of the ideal plasma model and enclosed space plasma.The results agree with CST simulation.Introduce resistive FSS in plasma and optimize the parameters with generic algorithm to form a new kind of plasma-FSS composite structure.It effectively reduces the plasma thickness and improves the plasma absorption effect.Establish equivalent circuit models of FSS in different materials and their parameters analysis,propose an average algorithm for equivalent circuit parameters with relatively high precision.Design a new absorption/transmission radome by using the plasma to control incident electromagnetic wave.It can reduce the risk of the antenna system detection and achieves low-frequency transmission and high-frequency absorption.The structure provides a novel way for radome design.3.Apply the plasma electromagnetic surface composed of plasma and FSS to shape stealth.It can achieve the reduction of the Radar cross section(RCS)of the incident electromagnetic wave.