Fundamental Research On Microwave Attenuation And Frequency Selective Transmission Effect Of Defect Heterogeneous Plasma Photonic Crystals

Microwave attenuation structure refers to a structure that hinders the propagation or absorption of electromagnetic waves in the microwave band.It has great application value in electromagnetic compatibility,microwave communication,microwave protection,radome and radar stealth.With the advancement of communication technology,communication equipment is developing towards miniaturization and integration.The application of multi-frequency communication puts forward higher requirements on the frequency selection characteristics and tunability of microwave attenuation structures.The traditional microwave attenuation structure has certain frequency selection characteristics,but it is generally not adjustable.Therefore,plasma,as a microwave attenuation structure with high frequency bandwidth,high efficiency and strong tunability,is a research hotspot in recent years.There are two main types of plasma in the application research of microwave attenuation frequency selective transmission: one is continuous distributed plasma,and the other is discrete distributed plasma.When the discretely distributed plasma is arranged periodically,it constitutes a plasma photonic crystal.Photonic crystals are composed of two or more materials with different electrical parameters arranged in a certain period in space.The frequency selection characteristics of emission/transmission are its basic functional properties and have important research value.The electrical parameters of the plasma are adjustable,so that the frequency selection characteristics of the periodic structure formed by the plasma can be adjusted,and it has broad application prospects.Summarizing the research status at home and abroad,the current research work of plasmonic photonic crystals is mainly one-dimensional and two-dimensional: one-dimensional plasmonic photonic crystals are mainly based on theoretical research,and the introduction of thin film absorbing materials to pursue broadband absorption is a representative direction..The two-dimensional plasma photonic crystal is mainly made of a plasma discharge tube into a microwave attenuation device for experimental research.Both usually have perfect and regular periodic characteristics.In solid state physics,defects in crystals can sometimes be used as a kind of "isomeric" functional structure to enhance the original performance of the crystal or obtain new properties.Inspired by this phenomenon,this paper proposes to introduce a defect structure into the plasma photonic crystal to form a new type of plasma photonic crystal microwave transmission control device with defects,and focus on its absorption and attenuation effects.This research topic is domestic There are few reports outside.Due to the introduction of defects,the number of cells in the plasma periodic structure will be greatly reduced,so as to achieve low power consumption of the device system and sparse array cells,which is conducive to solving the high power consumption bottleneck of plasma technology in aerospace platform engineering applications problem.In this context,this paper specifically studies the physical phenomena of electromagnetic wave propagation and scattering cross-section reduction in the sparse and heterogeneous characteristics of the angular defect structure in the two-dimensional plasma periodic structure.Through a combination of theory and experiment,Based on the effects of transmission and scattering suppression,the system design,simulation,sample measurement and other research work were carried out,and the following conclusions were drawn:1.Propose a heterogeneous plasma photonic crystal based on corner defects.In a two-dimensional periodic array with a truncation number of24,a thinning level of 8.3% to 25% is achieved.Through theoretical calculations and experimental measurements,the frequency-selective characteristics of microwave transmittance under different defect angles are studied.When the defect angle is 7.5°,the transmittance attenuation between the heterogeneous crystals with and without plasma is within 3d B.The frequency bands are 11.1GHz-12.6GHz and 13GHz-18 GHz,a total of6.5GHz,constituting the passband.The average attenuation of S21 in the passband is-0.17 d B,and the average attenuation outside the passband is-5.9d B.As the defect angle of the sample changes,the transmittance attenuation difference and frequency band can be adjusted accordingly.2.The scattering suppression effect of the heterogeneous crystal was studied through actual measurement in a compact field microwave anechoic chamber.The results showed that the sample with a defect angle of 22.5° produced an RCS reduction of more than-10 d Bsm on the flat target in the 8.3-10 GHz frequency band,and the defect angle was 7.5 °The sample produced an RCS reduction of more than-15 d Bsm for the flat target in the full frequency band of 8.2-12 GHz.The samples with the above-mentioned defect angles produced strong distortions to the scattering center distribution characteristics of the target.