Fundamental Study On The Reflective Characteristic Of Curved Surface Plasma Periodic Structures

The periodic electromagnetic structure has special electromagnetic properties and is a research hotspot of artificial electromagnetic structure.The plasma photonic crystal and frequency selective surface are typical objects in the field.Plasma photonic crystals are the intersection of plasma and photonic crystals which not only have the general characteristics of photonic crystals,but also with their unique properties when affected by the dispersion of plasma.The frequency selective surface has a tuning effect on electromagnetic waves and can be used as a filter,absorber,and other applications.However,it has been found in the study that even if the plasma has a high electron density which is equal to that of the metal,it does not exhibit an ideal cut-off characteristic,the electromagnetic wave still propagating.The electromagnetic wave can pass through when the penetration depth larger than the physical thickness of material;at the same time,it is difficult to produce a high enough electron density plasma in practice safely;it has been pointed that characteristics of a narrow absorption bandwidth and a large structural size are not conducive to miniaturization in the frequency selective surface.In response to the above problems,the following research work was mainly done:1.A novel plasma-composite periodic electromagnetic structure consisting of frequency selective surface and plasma photonic crystal has been proposed,which has the advantages of small scale and low density.The dispersion theory of one-dimensional plasma photonic crystal has been studied and expressions of the cutoff characteristics and the penetration depth have been obtained respectively.2.The research about structure design and parameter optimization on frequency selective surface has been carried out,and the topology parameters results of FSS which has absorption effect in 1~2GHz have been obtained.3.The error sources of the reflectivity test system have been analyzed.The experimental research work of plasma photonic crystal,frequency selective surface and plane plasma-composite periodic electromagnetic structure reflection characteristics has been carried out in the 1~2GHz and 8~12GHz frequency bands.The plasma frequency and the collision frequency have been diagnosed,and the electric field distribution results of the three structures at 1.2 GHz and 1.8 GHz have been obtained.4.The idea of curved plasma-composite periodic electromagnetic structure has been proposed.The experimental study on the curved plasma photonic crystal,the curved surface frequency and the curved plasmacomposite periodic electromagnetic structure have been carried out between the range of 1~18GHz and the results of the electromagnetic properties have been obtained.The influence of the radius of curvature on the reflection characteristics has been studied via experiment.The effects of the number of periodic elements making up curved composite structure on the radiation characteristics and electric field distribution have been studied at 1.06 GHz and 1.81 GHz5.The equivalent circuit model of the composite electromagnetic structure has been proposed.The equivalent impedance expression has been given.The relationship between the reflectivity and the model parameters has been qualitatively described.The mechanism of coupling effect between the plasma photonic crystal and the FSS has been explained.