| In 1998,Thomas Ebbesen et al.Studied the transmission characteristics ofperiodic subwavelength aperture arrays and found that there is an extraordinary optical transmission(EOT)effect when incident light waves pass through the metal film holes.Since then,the enhanced transmission has attracted many scholars'attention to the transmission characteristics of periodic subwavelength aperture arrays.With the deepening of research and the improvement of the fabrication technology,the study of EOT has broken through the traditional simple hole-seam structure and developed in new directions.Such as,multi-layer composite,hole-slit compound,terahertz band and microwave.At present,many scholars have done a great deal of research on the generation mechanism and application of EOT in simple structured light band.However,the EOT characteristics and their potential applications of multilayer composite structures have not been fully explored.Based on the theory of EOT,a metal-insulator-metal(MIM)enhanced-transmission structure is designed and its extraordinary characteristics are investigated in this paper.By introducing the EOT structure into the design of the microstrip antenna's cover layer structure,the gain of the antenna is effectively enhanceed,and the directivity of the antenna is improved.The main work of the paper has the following sections:1.This thesis introduces the research progress of EOT phenomenon at home and abroad and the research status of its applications in antennas.At the same time,the basic physical mechanism of the EOT is expounded.2.A MIM composite EOT structure with an embedded symmetric split Ring Resonators(SRR)is designed.The effects of such as the array period,the diameter of circular hole,the size of SRR,the spacing of SRR units and the thickness of the dielectric plate on the transmission characteristics of MIM composite structures are investigated.According to the distribution of current on the metal surface when extraordinary transmission is produced,the abnormal transmission is associated with the magnetic Plasmon resonance(MP),localized surface Plasmon(LSP),propagating surface plasmon(PSP),Fabry-Perot resonance(F-P)and the hybrid coupling among them.3.The quasi-periodic EOT structure is introduced into the design of antenna.A novel high-gain microstrip antenna is designed by using 6×6 enhanced transmission element array as the antenna cover layer on the simple microstrip antenna.Compared with the original antenna,the gain of the microstrip antenna with the EOT cover layer structure is improved by 5.2 dB.At the same time,the half-power beam width of the xoz and yoz planes is decreased by 32 degrees and 92 degrees respectively.The physical test and simulation results are in good agreement. |
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