We present a simple method for enhancing the bandwidth and absorptivity of metamaterial perfect absorber (MPA)-formed disk resonators. Utilizing low-conductivity polymer and near-field coupling of multi-band resonances, a 6.8 GHz broadband MPA is achieved with absorption over 90%. The proposed MPA also shows polarization-independent absorption behavior. Furthermore, the structural design is useful for making broadband MPA and can be applied to higher frequencies with a simple configuration.
This paper presents the design and simulation of polarization-independent type of metamaterial absorbers (MMAbs) at X-band frequency. The advantage of polarization-independent MMAbs is it can absorbs incident electromagnetic (EM) wave in all polarization states. It can be achieved by applying circular ring shape in a unit cell of MMAbs because the shape is very symmetry. The simulation is done in a unit cell for each proposed MMAbs structures. The FR4 substrate is used for MMAbs structure designs. The designed MMAbs structures can be divided into two parts which is circular ring and modified circular ring. The characteristics of both structure are studied through simulation process using CST software. Parametric study is conducted to observe the effect of each parameters in unit cell on the absorbing magnitude and frequency. It is observed that circular ring structures can achieve high EM wave absorbance for single band and multi band frequency. Since frequency separation distant limitation occurred, the modified circular ring structure is proposed by adding copper lines on the original circular ring structure. Thus, dual band frequency with close separation distant between two resonant frequencies is obtained as close as 1 GHz compared to the original dual band circular ring which is 2 GHz.
Broadband Polarization-Independent Perfect Absorber Using a Phase-Change Metamaterial at Visible Frequencies
