scholarly journals AN ULTRAWIDEBAND METAMATERIAL ABSORBER AND A PARAMETER RETRIEVAL METHOD

2019 ◽  
Author(s):  
JOSE BRUNO OLIVEIRA DE ARAUJO
Keyword(s):  
Metamaterial Absorber ◽  
Retrieval Method ◽  
Parameter Retrieval

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

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.

Single-peak-regulation and wide-angle dual-band metamaterial absorber based on hollow-cross and solid-cross resonators

2020 ◽  
Vol 91 (3) ◽  
pp. 30901
Author(s):  
Yibo Tang ◽  
Longhui He ◽  
Jianming Xu ◽  
Hailang He ◽  
Yuhan Li ◽  
...  
Keyword(s):  
Transverse Electric ◽  
Surface Current ◽  
Dielectric Substrate ◽  
Transverse Magnetic ◽  
Metamaterial Absorber ◽  
Absorption Peak ◽  
Dual Band ◽  
Single Peak ◽  
Wide Angle ◽  
Surface Current Density

A dual-band microwave metamaterial absorber with single-peak regulation and wide-angle absorption has been proposed and illustrated. The designed metamaterial absorber is consisted of hollow-cross resonators, solid-cross resonators, dielectric substrate and metallic background plane. Strong absorption peak coefficients of 99.92% and 99.55% are achieved at 8.42 and 11.31 GHz, respectively, which is basically consistent with the experimental results. Surface current density and changing material properties are employed to illustrate the absorptive mechanism. More importantly, the proposed dual-band metamaterial absorber has the adjustable property of single absorption peak and could operate well at wide incidence angles for both transverse electric (TE) and transverse magnetic (TM) waves. Research results could provide and enrich instructive guidances for realizing a single-peak-regulation and wide-angle dual-band metamaterial absorber.

Experimental Design as a Retrieval Method for Assessing the Phenomenological Characteristics of Episodic Memories, Episodic Future Thoughts, and Episodic Counterfactual Thoughts

2020 ◽  
Author(s):  
Jared Branch
Keyword(s):  
Experimental Design ◽  
Effect Sizes ◽  
Retrieval Method ◽  
Future Studies ◽  
Within Subjects ◽  
Demand Effects ◽  
Episodic Memories ◽  
Theoretical Considerations

Studies assessing the phenomenological characteristics of episodic memories, episodic future thoughts, and episodic counterfactual thoughts normally utilize a within-subjects design. As such, there are concerns that the observed similarities in phenomenological characteristics are the result of demand effects or other related matters, rather than theoretical considerations. In this study, a within-subjects experimental design was directly compared with a between-subjects experimental design. In both conditions, participants responded to existing questionnaires used to assess phenomenological characteristics of episodic memories, episodic future thoughts, and episodic counterfactual thoughts. The within-subjects design resulted more often in significant findings and larger effect sizes compared to the between-subjects design. The implications for experimental design in future studies is discussed.

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