The Study Of Metamaterial Absorber Based On Effective Medium

Metamaterial absorbers have some unique electromagnetic properties not existed in traditional absorbers, which open up a new way to new electromagnetic protective and target stealth materials. It is important to study the metamaterial absorbers because of the theoretical significance and application value. The main task of this work is to study the design, simulation, optimization, experiment and analysis the physical mechanism of the metamaterial absorber based on effective medium theory.In the first two chapters of the paper, a brief introduction of the metamaterial is presented, and the current status, practical applications and broadband absorber are summarized. Meanwhile, the effective medium theory, impedance matching theory and multiple interference theory related to the paper also introduced. Then, two kinds of metamaterial absorbers are studied in detail.Firstly, the design, fabrication, and measurement of a triple-band metamaterial absorber are presented, and the simulated results show that the proposed absorber can perform absorption peaks at three frequencies of 9.86 GHz,12.24 GHz, and 15.34 GHz with the absorption of 99.4%,96.7%, and 99.1%, respectively. In addition, the absorber can operate at a wide range of incident angles ranging from 0° to 60° with the absorption rate of more than 96% under both transverse electric and transverse magnetic polarizations. The surface current distributions and the electric energy distribution are utilized to explain the physical mechanism of the absorptions.Secondly, the simplified multi-reflection interference theory is proposed to analyze the physical insight quantitatively of the broadband metamaterial absorber loading lumped resisters. The simulated full width at half maximum absorption bandwidths is approximately 11.2 GHz with relative bandwidths of 116.7% for normal incidence electromagnetic wave. Microwave experiments are performed and measured results are in good agreement with the numerical results. The absorption of the proposed absorber calculated by the simplified multi-reflection interference theory coincide well with simulated and measured results. We perform parametric analyses by varying one parameter while keeping the other parameters fixed to reveal the optimization process of the proposed broadband metamaterial absorber.The proposed metamaterial absorbers have good electromagnetic characteristics of high absorption rate, polarization-insensitive and wide-angle incidence. More importantly, the effective medium theory is adopted to analysis physical mechanism of the broadband absorber loading lumped resistors, which provides a novel and effective computational method for analyzing metamaterial absorbers.