Modulation Of Radiation And Propagation Of Microwaves By Metamaterials

The “electromagnetic metamaterial” is one of the popular artificial material based on the arrangement of resonant units in the subwavelength scale in a lattice.Since the electromagnetic properties can be artificially controlled,metamaterials have some special properties which do not exist in natural materials.With the great adjust ability and numerous special physical properties,metamaterials have gained much research in electromagnetics and related areas,and it has been one of the research hotspots in both physics and material science.Therefore,the research about this electromagnetic metamaterial is of both theoretic and practiced interest.The main contents of this paper include:1 Firstly,the theoretical basis of artificial electromagnetic metamaterials is introduced,as well as the reason why these two parameters(permittivity and magnetic permeability)play a key role in its electromagnetic performance.The properties of left handed materials and zero-index metamaterial are discussed in detail.We analyze the produce mechanism of zero-index metamaterial and investigate the S parameters under different geometric structure parameters of material.In particular,we introduce the extraordinary optical transmission phenomenon of subwavelength metal hole array,find that it is caused by the spoof surface plasmon polariton which inspired by metamaterial.The surface plasmon polariton is also introduced as the foundation.2 Then,we mainly focused on the study of zero-refractive-index metamaterials on the improvement of the wavefront phase.We have analyzed the mechanism of the existence of zero-refractive-index metamaterials,designed a high-power metal-mesh antenna lens.Through numerical simulations,it is found that the zero-refractive-index lens can improve the wavefront phase of the horn antenna when covered on a KU band horn antenna's surface,The spherical front of the horn antenna is optimized into a more uniform wavefront of plane waves,the gain can be up to 2.27 dB,the power capacity of the horn antenna can reach 610 MW,thus high performance of the miniaturized antenna can be achieved.At the same time,the factor of influence on the S parameter is investigated,then the optimal structure parameters are obtained.3 The final part is on the spoof surface plasmon.Based on the tuning of geometric structures and parameters in left-handed materials,the artificial localized surface plasmon can be motivated,and even lead to extraordinary optical transmissionphenomenon.Firstly,three well-know mechanisms are introduced: the propagating surface plasmon resonance,the localized surface plasmon resonance and the complex diffraction evanescent waves.The transmission for the corrugated hole arrays drilled in perfect conductor films is investigated systematically in the microwave regime.The corrugation of the holes make the zero-order transmission of the hole array undergo a red shift compared with that of the uncorrugated hole array and thus realize extraordinary transmission at deeper subwavelength scales.The near-field patterns reveal that the localized modes on the corrugated holes play a key role in the resonant transmission.The investigations of the multipolar made of localized spoof SPP modes in the corrugated hole show that the dipolar mode is responsible for the extraordinary transmission.This scheme can extend to terahertz or infrared regime.