Conceptual-based design of an ultrabroadband microwave metamaterial absorber

Abstract

By introducing metallic ring structural dipole resonances in the microwave regime, we have designed and realized a metamaterial absorber with hierarchical structures that can display an averaged −19.4 dB reflection loss (∼99% absorption) from 3 to 40 GHz. The measured performance is independent of the polarizations of the incident wave at normal incidence, while absorption at oblique incidence remains considerably effective up to 45°. We provide a conceptual basis for our absorber design based on the capacitive-coupled electrical dipole resonances in the lateral plane, coupled to the standing wave along the incident wave direction. To realize broadband impedance matching, resistive dissipation of the metallic ring is optimally tuned by using the approach of dispersion engineering. To further extend the absorption spectrum to an ultrabroadband range, we employ a double-layer self-similar structure in conjunction with the absorption of the diffracted waves at the higher end of the frequency spectrum. The overall thickness of the final sample is 14.2 mm, only 5% over the theoretical minimum thickness dictated by the causality limit.

Underwater metamaterial absorber with impedance-matched composite

“…Because of the fundamental causal nature ( 41 – 43 ) of an absorber’s response to the incident wave, there is a minimum sample thickness associated with any given absorption spectrum A (λ). For acoustic systems, this causal constraint takes the form of an inequality ( 5 , 6 )d¯≥dmin=14π2BeffBnormalw∫0∞∣lnfalse(1−Afalse(normalλfalse)false)∣dnormalλwhere trued¯ denotes the average thickness of the absorber, and the value of static modulus, B eff / B w ≅ E c / B w = 1/5.5 in the present case.…”

“…Because of the fundamental causal nature (41)(42)(43) of an absorber's response to the incident wave, there is a minimum sample thickness associated with any given absorption spectrum A(). For acoustic systems, this causal constraint takes the form of an inequality (5, 6)…”

Three‐dimensional lightweight metamaterial with ultra‐wideband microwave absorption

“…While increasing the surface resistivity gradually, we can spread the high impedance of the magnetic resonances evenly over the frequency range in between the magnetic resonances. 16 The impedance matching condition of z ≈ 1 can be achieved in a wide range when the surface resistivity is set to 430 Ω/□, which results in a wide matching band with reflectivity below -10 dB.…”

“…For a small surface resistivity ( R → 0 Ω/□), Lorentzian type of resonance can be observed in the band from 500 MHz to 40GHz, where the real part of z exhibits high peaks at the magnetic resonance point while the impedance approaches zero at the electric resonance point. While increasing the surface resistivity gradually, we can spread the high impedance of the magnetic resonances evenly over the frequency range in between the magnetic resonances 16 . The impedance matching condition of z ≈ 1 can be achieved in a wide range when the surface resistivity is set to 430 Ω/□, which results in a wide matching band with reflectivity below ‐10 dB.…”

A Novel Meander Line Metamaterial Absorber Operating at 24 GHz and 28 GHz for the 5G Applications

“…Significant work on MA designs is available in the literature for microwave, terahertz, visible, and ultraviolet frequencies [ 13 , 14 , 15 , 16 , 17 , 18 ]. On the contrary, 5G and especially 24 GHz and 28 GHz bands are relatively unattended so far, in this regard [ 19 , 20 , 21 , 22 ]. Additionally, the limitations of previous works on narrowband, wideband, and ultra-wideband absorbers involve the facts of their complex geometrical structures, large number of layers to trap electromagnetic waves, and costly materials [ 13 , 14 , 15 , 16 , 17 , 18 , 23 , 24 , 25 , 26 ].…”