Manipulations To Physical Features Of Acoustic And Electromagnetic Wave Via Metamaterials

Metamaterials are artificial structure composed by periodic or aperiodic arrays of subwavelength unit cells.Some unprecedented effective parameters such as negative mass density ? and bulk modulus B for acoustic materials,or negative permittivity ? and permeability? for electromagnetic materials,which are not available in nature,can be obtained by designing the unit structure appropriately,thus providing new ways for the control of acoustic and electromagnetic fields.Although acoustic and electromagnetic waves are different essentially,their common characteristics give rise to the analogy between the two kinds of unit design.In this thesis,the physical properties of metamaterials in the two fields are analyzed by analogy.The main contents are summarized as follows:1.A microwave filter is designed based on one-dimensional(1D)spoof surface plasmon polariton(SSPP)structure.A M(?)bius Strip system in microwave band is investigated theoretically,and its eigenmode is calculated.The reflection and transmission properties are studied when the M(?)bius-like Strip system is coupled with the 1D SSPP structure.The simulation results are in good agreement with the theoretical analysis.This filter is a reflective-type filter with high quality factor.2.An acoustic multiband transmission structure based on the 1D spoof surface acoustic wave(SSAW)structure is designed.The dispersion relations of corrugated rigid body are investigated,and the corresponding acoustic field distributions in the groove are obtained.A new type of acoustic transmission line that supports multiband transmission of 1D SSAWs via high-order modes is also proposed,with the corresponding experimental results in good accordance with the simulation.To obtain a sensor at a subwavelength scale,the corrugated rigid disk,which can support spoof localized surface acoustic waves,is also optimized and validated through simulations.3.Based on two-dimensional(2D)extremely anisotropic electromagnetic metamaterials(EAEMM)structure,the lossless transmission of electromagnetic waves around sharp corners is realized and an electromagnetic cloak is proposed.The group velocity of transverse magnetic(TM)waves in 2D EA-electromagnetic medium(EM)and the propagation condition without backscattering are studied by theoretical analysis.The ultra-wideband characteristics are verified by observing the transmission of pulse signal within the sample.Both of them can be realized in ultrawide frequency range.4.Based on 2D EA-acoustic metamaterials(AMM)guided wave structure,the lossless transmission of acoustic waves around sharp corners can be realized and an acoustic cloak is proposed.Through theoretical analysis,we find that the group velocity of acoustic waves in EA-acoustic media(AM)only depends on the rotation angle of EA-AM,and its lossless propagation around sharp corner can be realized by designing the boundary and rotation angles between multi-layers of EA-AMs properly.Simulation results show that the design method works in ultra-wideband range.5.Extremely anisotropic 2D SSAWs guided wave structures,which are rigid structures composed of periodic hole arrays,are proposed to control the propagation paths of 2D SSAWs by arbitrary.The corresponding experimental results are in consistent with the simulation.The 2D SSAW is promising for integration in on-chip devices.