Study On Metamaterial Absorbers And Optimization

Along with the rapid development of science and technology, more and more attentions have been attracted to electromagnetic absorbing materials. The absorbing materials are playing the important role in weapons stealth, human body, instrument protection, and THz imaging.This paper first introduced the history and current situation of absorbing materials and electromagnetic metamaterials. We describe the origin, evolution and application of the metamaterial absorbers in detail and systematically analyze the absorbing principle of absorbers and Salisbury screen, which point out the realization conditions of ultra-thin absorbers.According to the basic principle of absorbing materials, we propose a novel absorbing structure which called Tetra-Arrow Resonator (TAR). The TAR absorber is a multi-band, wide-angle and polarization-insensitive absorber with excellent absorptivity and ultra-thin structure size. Waveguide experiments are conducted to verify the proposed designs effectively. The measurement results show that all of three absorptivity peaks come near to perfectionIn this paper, the properties of TAR absorber are further analyzed in depth. We first analyze the resonant modes of the three absorbing peaks based on the surface current distribution. And then we study the influence of effective impedance and loss characteristics of TAR absorber. Using the method of eigenmode we extract the resonant cavity model of TAR structure, and analyze the high order resonance and its absorbing response. In addition, we extract the effective permittivity, permeability and impedance of the TAR absorber which is treated as a whole material. We find that the TAR absorber has good impedance matching, large effective permittivity and permeability losses in three absorptivity peaks, which explains the principle of realization of the ultra-thin absorbing material according to the absorbing theory.We analyzed the radar cross section (RCS) of two kinds of finite periods of TAR absorbers, including flat and curved surfaces. It can be seen that the RCS of TAR structures are effectively reduced compared to the metal structure with same size. The results show the potential application of TAR absorbers in electromagnetic stealth.Finally, we develop a united simulation and optimization system which has the flexibility of optimization algorithm and the accuracy of the electromagnetic numerical calculation. The system is a very useful tool for electromagnetic fields optimization. We described the system composition and the method of realization. The effectiveness of the optimization system is verified by a random surface metamaterial absorber design.