Muti-physical Field Coupling Characteristics Of Flexible Metamaterial Structure

As an artificial composite material with unique electromagnetic properties,metamaterials have attracted extensive attention in the fields of microwave absorbers,antennas,and so on.As metamaterials are sensitive to the external environment,their properties are easily affected by mechanical field,temperature field and other factors.The traditional single physical field analysis can no longer meet the design requirements of metamaterials.It is necessary to introduce multi-physical field coupling analysis to explore their physical characteristics,so as to provide a theoretical basis for the application of metamaterials.Based on the above background,a novel broadband metamaterial absorber and a dual-band metamaterial antenna are designed based on the basic principle of metamaterial,and their multi-physical field coupling characteristics are analyzed.The main research contents of this thesis can be summarized as follows:1.A flexible broadband metamaterial absorber with transparent characteristics has been designed.The metamaterial is composed of indium tin oxide（ITO）resistance film and polyethylene terephthalate（PET）material,with periodic units of ITO-PET-ITO sandwich structure.The simulation results show that the absorptivity of metamaterial is above 90%from 10 GHz to 21.70 GHz,and the thickness is only 0.07λ₀（λ₀ is the wavelength corresponding to the lowest cut-off frequency）,which is polarization insensitive due to the symmetrical design of the structure.Then,the multi-physical field coupling simulation of metamaterial absorber is carried out.When the mechanical bending angle increases to 60°,the absorption band is expanded from 11.70 GHz to 15.40 GHz.The metamaterial absorber still has stable broadband absorbing properties in the range of-50℃-200℃.2.A flexible dual-band antenna with independent frequency tuning has been designed based on metamaterial theory.The designed metamaterial unit has magnetic single negative characteristic.Loading it on the traditional antenna can form a new working frequency band.Different radiation elements ensure that the two frequency bands can be controlled independently and reduce the mutual interference between the two bands.The working bandwidth of the metamaterial antenna is 2.30 GHz-2.61 GHz and 5.70 GHz-5.90 GHz,and the overall size is 0.24λ₀×0.20λ₀（λ₀ is the wavelength corresponding to 2.45 GHz）,and the thickness is only 0.001λ₀.Then,it is verified that the metamaterial antenna is less affected by mechanical deformation and has good flexibility.Finally,the electromagnetic-thermal-mechanical coupling characteristics of the metamaterial antenna are simulated and analyzed,and the results show that antenna still has stable radiation characteristics in the range of-50℃-200℃.3.The proposed metamaterial absorber and metamaterial antenna were processed by laser engraving and FPC technology respectively,and multi-physical field coupling measurement platform was built.The absorption performance of metamaterial absorber under mechanical deformation and the radiation characteristics of metamaterial antenna under different bending radius and different temperature were tested.The comparison shows that the measured results are consistent with the simulation results,which verifies the correctness of the simulation design.