Ling-Ling Wang

Comment on “Size-efficient metamaterial absorber at low frequencies: Design, fabrication, and characterization” [J. Appl. Phys. 117, 243105 (2015)]

In a recent article, Khuyen et al. [J. Appl. Phys. 117, 243105 (2015)] proposed a metamaterial perfect absorber (MPA) with a self-asymmetric structure and claimed that it could produce dual-band “perfect absorption.” In this report, we demonstrate that the self-asymmetric structure is not a true MPA. The cross-polarization reflection, which is induced by coupling between the induced magnetic field and the incident electric field, is ignored in calculation of absorptivity of that structure. The real absorption rate of this structure is below 60%, which indicates that the structure cannot be called a perfect absorber.

High-impedance surface-based flexible broadband absorber

Abstract In this paper, a novel broadband flexible metamaterial absorber, which is based on high impedance surface (HIS), has been investigated. The polarization-insensitive absorber can suppress the backward RCS by about 10 dBm2. Numerically simulated results indicate that the HIS metamaterial absorber (HIS-MA) obtains 11.14 GHz wide absorption from 6.86 to 18 GHz with the absorption over 90%. The results of experiment coincide with simulations, which prove the feasibility of HIS-MA. The flexibility and absorption performance of the HIS-MA is demonstrated by simulating and measuring the absorptivity as the absorber is bended on cylinders, which can obtain some novel properties. The simulated results of bistatic RCS showed that the bistatic RCS of HIS-MA bended on a cylindrical object is reduced by nearly 10 dBm2 compared with the conventional planar HIS-MA. The proposed absorber has more advantages in conformal applications than ordinary rigid absorber in its stealth property.

A novel broadband absorber with honeycomb lattices based on the flexible metamaterial

In this paper, a monolayer high-impedance surface broadband absorber with honeycomb lattices based on the flexible metamaterial are designed. The simulated results are shown that the relative absorption bandwidth is from 13 to 19.1 GHz, also it can be observed that the simulated absorption exceeds 95% almost from 13.1 to 19 GHz and the absorber is polarization insensitive for the incident wave under the normal incidence. Comparing with the bended absorber with traditional square lattices, the proposed absorber has advantages in the properties of absorbing. Even the bended absorber with honeycomb lattices has better absorption than the plane absorber. The proposed absorber can be worked as a polarization insensitive, conformal and broadband metamaterial absorber in radomes, cloaking and other microwave applications.

Omnidirectional photonic band gaps enlarged by 1D plasma photonic crystals with quasi-periodic structures

An omnidirectional photonic band gap (OPBG) in one-dimensional (1D) plasma photonic crystals (plasma-PCs) with fractal quasi-periodic structures, which are consisting of plasma and two isotropic dielectrics is theoretically calculated by the transfer matrix method (TMM). Compared to the Bragg gaps, the OPBG is not dependent on the angle of incidence and both transverse electric (TE) and transverse magnetic (TM) modes. The calculated results demonstrate that the 1D plasma-PCs with fractal quasi-periodic not only can obtain a larger bandwidth of OPBG but also have a shorter length in realizing devices.

A broadband flexible metamaterial absorber with a transparent window

A novel, broadband flexible metamaterial absorber is designed. The absorber is consisted of loaded high-impedance surfaces (HIS) on a flexible polyethylene terephthalate (PET) substrate and the back-metal layer replaced with a polarization-insensitive frequency-selective surface separated by a dielectric layer. The proposed absorber can obtain the bandwidth with the reflectivity below -10 dB in the frequency range of 7-16 GHz with a transparent window at 2.9 GHz. Losses in the high-impedance surface are introduced by printing the periodic pattern through resistive inks and hence avoiding the typical soldering of lumped resistors.