Realization of Bidirectional, Bandwidth-Enhanced Metamaterial Absorber for Microwave Applications

Abstract

The ever-increasing interest towards metamaterial absorbers owes to its remarkable features such as ultra-thin nature and design flexibility. Subduing the inherent narrow bandwidth of such absorbers is the prime goal in metamaterial absorber research, as this can widen the applications areas. A greater challenge is to construct bidirectional absorber, which provides direction-insensitive absorption, as most of the existing designs exhibit single sided absorption due to the complete metal film used in the design. This work presents the realization of a bidirectional, bandwidth-enhanced metamaterial absorber with basic elements such as strips and squares optimized to have adjacent resonances leading to a bandwidth-enhanced absorption. The structural evolution of the constituent metallic components towards the formation of bandwidth-enhanced absorption is described. The bidirectional absorber exhibits more than 90% absorption between 13.40 GHz and 14.25 GHz from the two incident directions. The mechanism of absorption is studied with the surface current analysis and the effective parameters of the structure. The choice of the metallic components with four-fold rotation symmetry renders the proposed design to be polarization independent and wide-angle receptive. The numerical studies are verified experimentally at microwave frequencies, which shows a good agreement between them.

Enhanced broadband absorption with a twisted multilayer metal–dielectric stacking metamaterial

“…However, the combination of a single resonant peak will inevitably lead to severe fluctuation of absorption within the desired bandwidth. [16][17][18] To flat the absorption spectrum of broadband MA, another method is to vertically align the multilayer patterns (vertical arrangement) to superpose a series of narrow-band absorption peaks in order to form a broadband absorption. [19][20][21][22] Moreover, the superposed structure also reduces the unit size compared with the planar arrangement method.…”

Wide-band metamaterial perfect absorber through double arrow shape printed on a thin dielectric

“…Past researchers have developed wide-band absorber by using various technique, subject to the main constrain of the structure. Although some applied patterned ground planes are less complicated to develop, they lack of the bandwidth increment [26], [27]. A bidirectional absorber with metal patterns on both sides of the dielectric substrate may be used, but, it is not achievable by a mere duplication of metallic patterns.…”

Multiple-Band Terahertz Metamaterial Absorber Using Multiple Separated Sections of Metallic Rectangular Patch

“…Multiple-band metamaterial absorbers mean that they enable perfect absorption at several discrete frequency points. According to the number of frequency points [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28], the multiple-band absorption devices can be divided into dual-band absorption, triple-band absorption, quad-band absorption, and even more. In terms of design ideas, the principles of these multiple-band metamaterial absorbers are similar that they are resulted from the combined effect of the single resonance response of each metallic resonator.…”

“…In terms of implementation modes, the realization of the multiple-band metamaterial absorbers usually has two methods. One of which is the co-planar design method for placing multiple sub-resonators [9][10][11][12][13][14][15][16][17][18][19][20][21]. However, this type of design is at the expense of increasing the interaction of the subarrays (resulting in weak absorption strength) and expanding the unit size (resulting in large and non-compact structure size).…”

“…The performance of the multiple-band absorption shows a significant dependence on the gap sizes, number, as well as the gap position in the rectangular patch. Compared with the existing design technologies of realizing multiple-band absorption [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28], the multiple-band absorption device has some superior features, especially it does not increase the transverse and longitudinal dimensions of the basic cell, so it can effectively avoid the coupling effect of the sub-structures in the large-sized co-planar design method and can avoid the timeconsuming fabrication steps and complex structure faced in the layered design approach. Therefore, the multiple-band terahertz metamaterial absorber should have a wide range of application prospects in the terahertz technology related fields, including terahertz imaging, terahertz detection, terahertz sensing, etc.…”