Design And Research Of A Broadband Metamaterial Absorber At Microwave Frequency

Metamater ial absorber(MA) is a kind of artific ial composite material. The electromagnetic waves that projected on the surface of MA can be absorbed as much as possible and have almost no reflection and transmission. MAs have important applicat ions in var ious fields such as military stealth, radiation shielding, so they have gained more and more attentions. This paper mainly researches the design and characteristics of our absorber and the realization of broadband MA. The main contents of this paper can be summarized as follows:This paper present a new kind of absorbing structure, the structure is compact and has high absorption intensity. The metamaterial absorber which is constructed of a periodic array of this structure is four-band polarizat ion- insensit ive and wide-angle incidence. Simulat ion results clearly show that the absorption ratios at four absorption points are all higher than 96%, and the relat ive bandwidth with absorption intensity greater than 50% is 15.74%. When the incident angle changes from 0deg to 60 deg, for TE polarizat ion, the structure has the wide-angle insensit ive characteristic, and for TM polarization, at the relative low frequency range(10--14GHz), the absorber is angle-insensit ive, while at the relat ive high frequency range(20--25GHz), an addit ional is presented. Subsequently, the electric field and surface current are analyzed to research the principle of this absorber, and the reason of additional absorption peak at TM polar izat ion is explained. Besides, the loss analysis is researched from the dielectric loss and ohmic loss. Moreover, the effective electromagnetic parameters are retrieved to explain the reason of high absorptivity. Finally, the influences of geometrical parameters to absorptivity are introduced briefly.Metamater ial absorber can achieve perfect absorption by manipulating their geometrical parameters, but the bandwidths of most MAs have been reported are fairly narrow. Therefore the applications of such metamaterial absorbers are limit ed, so broadening the bandwidth of metamaterial absorber is a general concerned problem for researchers. To enhance the absorption bandwidth of the absorber, 1?2 array and 2 ?2 array in one unit cell are designed by adjusting the geometrical parameters. The simulat ion results clear ly show that in 1?2 array, the bandwidth is 3.655 GHz, and the relative bandwidth is increased from 15.74% to 20.69% under EM wave normal incidence.; in 2 ?2 array, for TE wave normal incidence the bandwidth is 3.368 GHz, and the relative bandwidth is increased from 15.74% to 20.03%, and for TM wave normal incidence the bandwidth is 4.085 GHz, and the relative bandwidth is increased from 15.74% to 24.15%.