Ultra-thin wideband magnetic-type metamaterial absorber based on LC resonator at low frequencies

Abstract

In this paper, we propose to realize a broad absorption band in the frequency regimes of 2-6 GHz based on multiple resonances. A magnetic-type metamaterial absorber with cross-arrow pattern is further demonstrated numerically and experimentally. Two absorption resonances are generated by LC resonance, leading to bandwidth expansion. The equivalent circuit theory and the surface current distributions of the proposed absorber are discussed to analyze the physical mechanism. Moreover, the broad bandwidth can be maintained as incident angle up to 30°for transverse electric polarization and 45°for transverse magnetic polarization. Finally, experimental results show that the proposed absorber with the total thickness of 2.4 mm exhibits a -10 dB absorption bandwidth by more than 70 %. The low-frequency absorber has potential applications in the area of eliminating microwave energy.

Metamaterial Absorbers: From Tunable Surface to Structural Transformation

“…The periodic patterns are represented through an RLC circuit model, in which the equivalent impedance ( Z u ) can be described in following equation [ 47,51,52 ] $$\[{Z_{\rm{u}}} = R + j\omega L + \frac{1}{{j\omega C}}\]$$where R , C , and L are equivalent resistance, capacitance, and inductance of the periodic patterns. For the dielectric spacer backed by the ground plane, the equivalent impedance ( Z t ) is expressed as [ 53 ] $$\[{Z_{\rm{t}}} = j{Z_0}\sqrt {{\mu _{\rm{r}}}{\rm{/}}{\varepsilon _{\rm{r}}}} \tan (\omega t\sqrt {{\mu _0}{\varepsilon _0}{\mu _{\rm{r}}}{\varepsilon _{\rm{r}}}} )\]$$where Z 0 is the impedance of free space (377 Ω), μ r and ε r , μ 0 and ε 0 are permeability and permittivity of dielectric spacer and the vacuum, ω is the angular frequency of incident wave, and t is the thickness of dielectric spacer. Then, the input impedance of the MA ( Z in ) is given by $$\[\frac{1}{{{Z_{{\rm{in}}}}}} = \frac{1}{{{Z_{\rm{u}}}}} + \frac{1}{{{Z_{\rm{t}}}}}\]$$…”

“…where R, C, and L are equivalent resistance, capacitance, and inductance of the periodic patterns. For the dielectric spacer backed by the ground plane, the equivalent impedance (Z t ) is expressed as [53] / tan( )…”

A miniaturized high‐performance broadband absorber based on 2. 5‐D meander lines and magnetic materials at low frequencies

“…Magnetic materials (MM) are always a hot area of absorbing materials research due to its high permittivity and permeability and its good characteristic of impedance matching and reflection loss 11–13 . Rozanov has illustrates the ultimate problems of the bandwidth ratio of metal‐backed magnetic absorbing materials absorbers 14 …”

Design of a Tunable Absorber Based on Active Frequency-Selective Surface for UHF Applications

“…Metamaterial absorbers (MMA) have attracted much attention in recent years [8,9,10,11,12,13,14], after a perfect MMA with near unity absorption in microwave regime was first reported by Landy et al [15]. MMA are also used for low frequency applications [16,17,18,19]; for example, Khuyen et al [20] proposed an ultrathin polarization-insensitive metamaterial absorber, which exhibits a peak absorption of 97% at 250 MHz. Zuo et al [21] presented a wideband metamaterial absorber using a metallic incurved structure, which has an absorptivity of more than 90% at 0.8–2.7 GHz.…”