Ultra‐thin metamaterial perfect absorbers for single‐/dual‐/multi‐band microwave applications

Abstract

In this study, the authors present three different metamaterial absorbers (MMAs) namely, T, split‐I (SI) and split‐Jerusalem cross (SJC) with different dimensions and geometrical configurations. The absorption rates of T‐, SI‐ and SJC‐shaped absorbers are studied at microwave frequencies. T‐shaped absorber demonstrates perfect absorption at 10.19 GHz, making it suitable for single band operation, whereas SI‐shaped absorber exhibits two perfect absorption peaks at 9.32 and 10.75 GHz finding its application in dual band operation. However, novel SJC‐shaped absorber demonstrates multiple absorption peaks at 9.92, 10.42, 10.93, 11.75 and 13.25 GHz with absorption of 99.5, 91, 99.9, 91.8 and 99.6%, respectively, making it suitable for X‐ and Ku‐band operations. The proposed MMAs have a thickness of around 0.8 mm (i.e. <λ/37) with respect to the lowest frequency of operation. Furthermore, the absorbers are analysed for different angles of polarisation and incidence for transverse electric polarised wave with a step size of 15°. The proposed absorbers have been fabricated and experimentally demonstrated at X‐band verifying the results obtained from simulations and implementing an equivalent circuit method. Further, SJC‐shaped absorber is demonstrated for multi‐and wide‐band terahertz applications exhibiting four perfect absorption peaks at 2.76, 2.89, 3.02 and 3.31 THz.

An Ultrathin Compact Polarization-Sensitive Triple-band Microwave Metamaterial Absorber

“…17 The polarization-sensitive nature of the structure demonstrates the practical applications in various fields including polarization detection and sensing. 17,18 Further, it is observed that the absorber is insensitive to incident angles till 45 o , and after that, absorption is reduced with increase in the angle, as illustrated in Fig. 4b.…”

“…As shown in Fig. 3a, the normalized impedance (Z) 9,18 of the proposed absorber is 0.88 + j0.08, 1.07 À j0.18 and 1.04 À j0.03 at 3.36 GHz, 3.95 GHz and 10.48 GHz, respectively. The equivalent circuit for the proposed absorber given in the inset of Fig.…”

“…3a is analogous than that of the previously reported studies. 9,18,23,24 Figure 3b and c demonstrates the constitutive EM parameters (e eff and l eff ), to understand the physical mechanism of the absorber. The values of the real and imaginary values of e eff and l eff should be almost same at all resonating frequencies as structure impedance equals the free space impedance, leading to zero reflection.…”

“…6 These structures have the ability to minimize the reflection by matching the impedance of the MMA to free space, and the transmission is eliminated by the ground plane to achieve perfect absorption. 8 Till now, various metamaterial-based structures have been investigated, including split-ring structures, 11 ring-shaped, 14,15 square-shaped, 10,16 cutwire 17 and spilt-Jerusalem cross-resonators 18 to demonstrate their performance with dual-, 11,14,17,19 triple-, 15,17,20 multi- 16,18 and broadband 10 operations. To achieve multi-band absorption performance, several efforts have been carried out using orthogonal arrangements of different metallic resonators 10,17 or multilayered metallic structures separated by dielectric substrates.…”

“…In addition, several MMAs with polarization-sensitive characteristics have been demonstrated and have drawn significant attention due to their applications in polarization detection and imaging. 17,18 Despite previous studies on various MMAs, a few reports are available on the design of an ultra-thin and compact absorbers exhibiting perfect absorption and polarization-insensitive characteristics. Hence, here, we present a compact and ultra-thin MMA demonstrating the perfect absorption phenomenon for S-and X-band applications.…”