In this paper, we present the design, simulation, and measurement of a dual-band metamaterial absorber in the microwave region. Simulated and experimental results show that the absorber has two perfect absorption points near 11.15GHz and 16.01GHz. Absorptions under difierent polarizations of incident EM waves are measured with magnitude of over 97% at low-frequency peak and 99% at high-frequency peak respectively. Current distribution at the dual absorptive peaks is also given to study the physical mechanism of power loss. Moreover, it is verifled by experiment that the absorptions of this kind of metamaterial absorber remain over 90% at the low-frequency peak and 92% at the high-frequency peak with wide incident angles ranging from 0 - to 60 - for both transverse electric wave and transverse magnetic wave.

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Perfect Metamaterial Absorber with Dual Bands

A general and readily applicable scheme is presented for the determination of the basis functions that allow the decomposition of the surface current into a solenoidal part and a nonsolenoidal remainder. The proposed approach brings into correspondence these two parts with two scalar functions and generates the known loop and star basis functions. The completeness of the loop-star basis is discussed, employing the presented scheme; the issue of the irrotational property of the nonsolenoidal functions is addressed.

Loop-star decomposition of basis functions in the discretization of the EFIE

The design and realization of a multi-band and polariza- tion insensitive metamaterial absorber is presented. The structure with thickness 1.1mm consists of six close rings which distribute in two metallic layers separated by FR4 flber glass PCB substrates. Ex- perimental results show that over 93.3% absorption can be achieved in this metamaterial absorber at multiple frequency bands (more than two). Due to the rotational symmetric pattern of the metamaterial, the performance of the absorber is insensitive to the polarization of the incident waves, indicating the superiority of the structure in the application.

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Multi-band and polarization insensitive metamaterial absorber

In this study, we designed a dual-chirality hierarchical structure to achieve a synergistically enhanced effect in microwave absorption via the hybridization of nanomaterials. Herein, polyaniline (PANi) nanorods with tunable chirality are grown on helical carbon nanotubes (HCNTs), a typical nanoscale chiral structure, through in situ polymerization. The experimental results show that the hierarchical hybrids (PANi@HCNTs) exhibit distinctly dual chirality and a significant enhancement in electromagnetic (EM) losses compared to those of either pure PANi or HCNTs. The maximum reflection loss of the as-prepared hybrids can reach -32.5 dB at 8.9 GHz. Further analysis demonstrates that combinations of chiral acid-doped PANi and coiled HCNTs with molecular and nanoscale chirality lead to synergistic effects resulting from the dual chirality. The so-called cross-polarization may result in additional interactions with induced EM waves in addition to multiscaled relaxations from functional groups and interfacial polarizations, which can benefit EM absorption.

Synergistic Enhancement of Microwave Absorption Using Hybridized Polyaniline@helical CNTs with Dual Chirality

MULTILAYER SYSTEM OF LORENTZ/DRUDE TYPEMETAMATERIALS WITH DIELECTRIC SLABS AND ITSAPPLICATION TO ELECTROMAGNETIC FILTERSC. SabahPhysikalisches InstituteJohann Wolfgang Goethe UniversityMax-von-Laue-Strasse 1, D-60438, Frankfurt am Main, GermanyS. UckunElectrical and Electronics Engineering DepartmentUniversity of GaziantepGaziantep 27310, TurkeyAbstract—In this work, frequency behavior of the multilayerstructure comprised of double-negative (DNG) and dielectric slabs ispresented in detail. The multilayer structure consists of

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Multilayer System of Lorentz/Drude Type Metamaterials with Dielectric Slabs and its Application to Electromagnetic Filters

This study presents the electromagnetic wave propagation through the frequency-dispersive and lossy double-negative slab embedded between two different semi-infinite media. The double-negative slab is realized by using two models, the Lorentz and Drude medium models. The properties and the required equations for the frequency-dispersive and lossy double-negative slab, the Lorentz medium and Drude medium are given in detail. After the construction of the problem, the reflection and transmission coefficients are derived for both TE and TM waves. Then, the reflected, transmitted and loss powers are determined using these coefficients. Finally, in the numerical results, the mentioned powers for TE and TM waves are computed and illustrated as a function of the incidence angle, the frequency and the slab thickness when the damping frequency changes.

Electromagnetic wave propagation through frequency-dispersive and lossy double-negative slab

We presented the microwave experiments with a new metamaterial composed of triangular split ring resonators (TSRRs) and wire strip at microwave regime. The transmission measurements were performed in free space for two LHM samples which have different number of TSRRs and wire strips. The experimental results show that the left-handed transmission peak stands in the frequency band where both the permittivity and permeability are negative. It is also observed that left-handed transmission band can be shifted if the number of TSRRs and wire strips are changed.

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Transmission measurements of a new metamaterial sample with negative refraction index

This paper presents a general analysis of reflection and transmission coefficients of multiple chiral layers in detail. Reflection and transmission coefficients through multiple chiral layers are computed and presented particularly for the incident wave of parallel polarization for a number of cases―a wide range of incidence angle, neigh- boring center frequency and different chirality parameters. Transfer matrix method is used in the analysis. From the numerical results, it can be seen that multiple chiral layers may be used as a polarization-conversion transmission filter and antireflection filter at the frequency band around the central frequency.

Reflection and transmission coefficients of multiple chiral layers

A new numerical procedure is developed for the solution of the electric field integral equation (EFIE) for arbitrary-shaped microstrip structures. This approach is superior over conventional EFIE techniques particularly in the low-frequency region or where the structure to be analyzed is electrically small. A pair of new basis functions is presented which are essential to the solution in the entire frequency range of interest. The new basis functions decompose the surface current density into divergenceless and curl-free parts which essentially get decoupled at the very low end of the frequency spectrum. Typical numerical results are presented for certain examples to illustrate the difference in the results between the two methods.

S. Uckun

Papers

Multilayer System of Lorentz/Drude Type Metamaterials with Dielectric Slabs and its Application to Electromagnetic Filters

Electromagnetic wave propagation through frequency-dispersive and lossy double-negative slab

Transmission measurements of a new metamaterial sample with negative refraction index

Reflection and transmission coefficients of multiple chiral layers

A novel technique for analysis of electromagnetic scattering from microstrip antennas of arbitrary shape