The Study Of Water-based Wideband Metamaterial Absorber

Metamaterials are a new type of artificial structure.They have electromagnetic characteristics not found in matter in nature,such as negative refraction,perfect absorption,and inverse Doppler effects.They have been widely used and studied in electromagnetic wave absorbers,high-performance antennas,and sensors.This thesis reviews the definition of metamaterials,related basic properties,the origin and development of metamaterials,and the application of metamaterials.It describes the analysis theory of metamaterial absorbers in detail,including equivalent medium theory,surface current analysis methods,and so on.The thesis focuses on the research of the all-dielectric design method of metamaterial absorbers.Using water and 3D printing technology,two ultra-wideband water-based metamaterial absorbers are designed and manufactured:one is a "I" shaped water-based metamaterial ultra-wideband absorber.The simulation and experiments have shown that the absorber absorbs electromagnetic waves more than 90%in the frequency range of 7.9-21.7GHz.It has a wide incident angle working ability,polarization insensitivity and temperature insensitivity.The other is a "+"ladder type water-based metamaterial flexible absorber,which extends the planar absorber to a curved structure.Simulations and experiments have demonstrated that the presented absorber works well in the 5.5-27.5GHz frequency range,and the curved absorber is almost perfect uniform absorption in the range of 5-40GHz.In addition,the absorption mechanism of the absorbers is discussed and analyzed in detail for the two models from the aspects of the structure of the absorbers,the energy distribution of the electric field,and the equivalent impedance.The proposed water-based absorbers have the advantages of simple structure,easy production,low production cost,and strong ability to adapt to the environment.Especially the flexible absorber with curved surface is suitable for conformal with complex structures,and has certain application value in the fields of radar target stealth and electromagnetic compatibility.