scholarly journals Causal homogenization of metamaterials

Nanophotonics ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 1063-1069 ◽  
Author(s):  
SeokJae Yoo ◽  
Suyeon Lee ◽  
Jong-Ho Choe ◽  
Q-Han Park
Keyword(s):  
Effective Thickness ◽  
Causality Condition ◽  
Phase Ambiguity ◽  
Effective Parameters ◽  
Retrieval Method ◽  
Minimum Error ◽  
Homogenization Scheme ◽  
Logarithm Function ◽  
Parameter Retrieval ◽  
Error Condition

AbstractWe propose a homogenization scheme for metamaterials that utilizes causality to determine their effective parameters. By requiring the Kramers-Kronig causality condition in the homogenization of metamaterials, we show that the effective parameters can be chosen uniquely, in contrast to the conventional parameter retrieval method which has unavoidable phase ambiguity arising from the multivalued logarithm function. We demonstrate that the effective thickness of metamaterials can also be determined to a specific value by saturating the minimum-error condition for the causality restriction. Our causal homogenization provides a robust and accurate characterization method for metamaterials.

scholarly journals Fractal Acoustic Metamaterials with Subwavelength and Broadband Sound Insulation

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Yu Liu ◽  
Meng Chen ◽  
Wenshuai Xu ◽  
Tao Yang ◽  
Dongliang Pei ◽  
...  
Keyword(s):  
Low Frequency ◽  
Sound Insulation ◽  
Acoustic Metamaterials ◽  
The Finite Element Method ◽  
Transmission Losses ◽  
Effective Parameters ◽  
Retrieval Method ◽  
Sound Control ◽  
S Parameter ◽  
Broadband Sound

We construct new fractal acoustic metamaterials by coiling up space, which can allow subwavelength-scale and broadband sound insulation to be achieved. Using the finite element method and the S-parameter retrieval method, the band structures, the effective parameters, and the transmission losses of these acoustic metamaterials with different fractal orders are researched individually. The results illustrate that it is easy to form low-frequency bandgaps using these materials and thus achieve subwavelength-scale sound control. As the number of fractal orders increase, more bandgaps appear. In particular, in the ΓX direction of the acoustic metamaterial lattice, more of these wide bandgaps appear in different frequency ranges, thus providing broadband sound insulation and showing promise for use in engineering applications.

An Ultrathin and Ultrawideband Metamaterial Absorber and an Equivalent-Circuit Parameter Retrieval Method

2020 ◽  
Vol 68 (5) ◽  
pp. 3739-3746 ◽  
Author(s):  
Jose Bruno O. de Araujo ◽  
Glaucio L. Siqueira ◽  
Erich Kemptner ◽  
Mauricio Weber ◽  
Cynthia Junqueira ◽  
...  
Keyword(s):  
Equivalent Circuit ◽  
Metamaterial Absorber ◽  
Circuit Parameter ◽  
Retrieval Method ◽  
Parameter Retrieval ◽  
Equivalent Circuit Parameter

scholarly journals Predicting double negativity using transmitted phase in space coiling metamaterials

2018 ◽  
Vol 5 (5) ◽  
pp. 171042 ◽  
Author(s):  
Santosh K. Maurya ◽  
Abhishek Pandey ◽  
Shobha Shukla ◽  
Sumit Saxena
Keyword(s):  
Acoustic Waves ◽  
Negative Refraction ◽  
Acoustic Properties ◽  
Propagation Path ◽  
Elastic Response ◽  
Acoustic Metamaterials ◽  
Effective Response ◽  
Retrieval Method ◽  
S Parameter ◽  
Parameter Retrieval

Metamaterials are engineered materials that offer the flexibility to manipulate the incident waves leading to exotic applications such as cloaking, extraordinary transmission, sub-wavelength imaging and negative refraction. These concepts have largely been explored in the context of electromagnetic waves. Acoustic metamaterials, similar to their optical counterparts, demonstrate anomalous effective elastic properties. Recent developments have shown that coiling up the propagation path of acoustic wave results in effective elastic response of the metamaterial beyond the natural response of its constituent materials. The effective response of metamaterials is generally evaluated using the ‘S’ parameter retrieval method based on amplitude of the waves. The phase of acoustic waves contains information of wave pressure and particle velocity. Here, we show using finite-element methods that phase reversal of transmitted waves may be used to predict extreme acoustic properties in space coiling metamaterials. This change is the difference in the phase of the transmitted wave with respect to the incident wave. This method is simpler when compared with the more rigorous ‘S’ parameter retrieval method. The inferences drawn using this method have been verified experimentally for labyrinthine metamaterials by showing negative refraction for the predicted band of frequencies.

An electromagnetic parameter retrieval method based on deep learning

2020 ◽  
Vol 127 (22) ◽  
pp. 224902
Author(s):  
Siqi Huang ◽  
Zilong Cao ◽  
Helin Yang ◽  
Zhaoyang Shen ◽  
Xiaoxia Ding
Keyword(s):  
Deep Learning ◽  
Electromagnetic Parameter ◽  
Retrieval Method ◽  
Parameter Retrieval

Study on dynamic effective parameters of bilayer perforated thin-plate acoustic metamaterials

2020 ◽  
pp. 2150048
Author(s):  
Yicai Xu ◽  
Jiu Hui Wu ◽  
Yongqing Cai
Keyword(s):  
Thin Plate ◽  
Thin Plates ◽  
Formation Mechanisms ◽  
Acoustic Metamaterials ◽  
Effective Parameters ◽  
Retrieval Method ◽  
Acoustic Metamaterial ◽  
Resonance Frequencies ◽  
Wave Normal ◽  
Mass Type

In this paper, dynamic effective parameters of mass-type and stiffness-type bilayer perforated thin-plate acoustic metamaterials (MBPM and SBPM) are investigated by simulations and experiments. Dynamic effective parameters are calculated by the retrieval method, and formation mechanisms of special effective parameters are analyzed by simulated fields. Divergent effective parameters are produced by anti-resonances of coupled perforations or coupled perforated thin-plates, zero effective parameters are produced by resonances of coupled perforated thin-plates. The impacts of perforation parameters on dynamic effective parameters for symmetric and asymmetric BPMs are systemically studied, the simulated and experimental results both show that variation trends of resonance and anti-resonance frequencies of mass-type bilayer perforated thin-plate acoustic metamaterial (MBPM) are different from stiffness-type bilayer perforated thin-plate acoustic metamaterial (SBPM), because perforations mainly change system mass in MBPM and system stiffness in SBPM, respectively. Dynamic effective parameters are bi-anisotropic in asymmetric BPM, and doubly negative effective parameters are achieved by coupled perforations when plan wave normal incident from the side with smaller perforation parameters. A modified retrieval method is proposed to calculate unified effective parameters for the asymmetric BPM, and the unified effective parameters equal to averaged effective parameters of two symmetric BPMs. This work systematically studies dynamic effective parameters of bilayer perforated structures, which has a great guiding significance in design of perforated acoustic devices.

Obtaining Directly Quasi-Square Open Ring FSS Constitutive Effective Parameters by Using Coupled WCIP - Retrieval Method

2019 ◽  
Vol 397 ◽  
pp. 187-199
Author(s):  
Saida Mellal ◽  
Toufik Ziar ◽  
Hichem Farh ◽  
Khalid Hati ◽  
Badreddine Zemmal ◽  
...  
Keyword(s):  
Frequency Selective Surface ◽  
Electric Permittivity ◽  
Scattering Parameters ◽  
Effective Parameters ◽  
Retrieval Method ◽  
Matlab Program ◽  
Open Ring ◽  
Analytical Formulas ◽  
Frequency Selective ◽  
Constitutive Parameters

We propose here a method witch analyze the behavior of Quasi-square open ring frequency selective surface (FSS) by using an approach based on the wave iterative concept procedure method (WCIP) coupled to Retrieval from Scattering Parameters method . The scattering parameters calculated by WCIP for a Quasi-square open ring FSS are used, in analytical formulas, to calculate directly observable effective constitutive parameters (relative electric permittivity εreff , magnetic permeability μreff and refractive index n ) of a frequency selective surface. Results of effective constitutive parameters for a Quasi-square open ring FSS structure are presented by Simulation using MATLAB program codes translating the implementation of the proposed approach.

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