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Special Issue "Electromagnetic Wave Absorbing Structures"

A special issue of Materials (ISSN 1996-1944).

Deadline for manuscript submissions: closed (30 September 2018)

Special Issue Editors

Guest Editor
Prof. Mario Marchetti

Department of Astronautic Electric and Energy Engineering, Sapienza University of Rome, Via Eudossiana 18, 00184 Rome, Italy
Website | E-Mail
Interests: materials science; aerospace structures.
Guest Editor
Dr. Davide Micheli

Department of Wireless Access Engineering, Telecom Italia S.P.A, Viale Parco de' Medici, 61-00148 Rome, Italy
Website | E-Mail
Interests: radar absorbing structures; electromagnetic weave propagation in lossy media; mobile telecommunications technologies; material science.

Special Issue Information

Dear Colleagues,

Electromagnetic Wave Absorbing Structures are becoming an important topic in most technologies and environments where the main focus is to reduce the level of electromagnetic fields in certain places or systems. In particular, they are employed in reducing radar signature and/or the power density of electromagnetic interference in defence, telecommunication, medical systems, laboratory environments, and in human health care and public safety issues too. In systems where electromagnetic shielding effectiveness need to be improved, absorbing materials play a central role in lower down the amount of reflected and transmitted electromagnetic waves. Typically, the lower the frequency the harder to build effective absorbers at the cost of increased final thickness. Nowadays, some research on electromagnetic wave absorbers is focused on monolayer structures, whereas others make use of layered structures. Recently, these last have also been successfully applied to mimic reflection coefficient profiles, a priori established in metrology and defense technologies. Research works currently span electric and magnetic properties of materials to improve electromagnetic wave absorbing capabilities. In such a contest, most studies make use composites made with carbon nanoparticles. Other research is focused on foamed structures.

We invite full papers, communications, and reviews that cover one or several of the listed keywords below.

Prof. Mario Marchetti
Dr. Davide Micheli
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Materials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Electromagnetic wave absorbers based on composites and thermoplastic materials
  • Electromagnetic wave absorbers based on foam structures
  • Electromagnetic wave absorbers based on nanoparticles
  • Electromagnetic wave absorbers based on multilayer structures
  • Electromagnetic wave absorbers based on fibrous structures

Published Papers (7 papers)

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Research

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Open AccessArticle
Ultra-Wideband and Wide-Angle Microwave Metamaterial Absorber
Materials 2018, 11(10), 2045; https://doi.org/10.3390/ma11102045
Received: 28 September 2018 / Revised: 17 October 2018 / Accepted: 19 October 2018 / Published: 20 October 2018
Cited by 1 | PDF Full-text (2203 KB) | HTML Full-text | XML Full-text
Abstract
In order to extend the performance of radar absorbing materials, it is necessary to design new structures with wideband properties and large angles of incidence which are also as thin as possible. The objective of this work, realized within the framework of the [...] Read more.
In order to extend the performance of radar absorbing materials, it is necessary to design new structures with wideband properties and large angles of incidence which are also as thin as possible. The objective of this work, realized within the framework of the SAFAS project (self-complementary surface with low signature) is, then, the development of an ultra-wideband microwave absorber of low thickness. The design of such material requires a multilayered structure composed with dielectric layers, metasurfaces, and wide-angle impedance matching layers. This solution has been realized with on-the-shelf materials, and measured to validate the concept. At normal incidence, the bandwidth ratio, defined for a magnitude of the reflection coefficient below −10 dB, is 4.7:1 for an absorber with a total thickness of 11.5 mm, which corresponds to λ/7 at the lowest operating frequency. For an incidence of 60°, this bandwidth ratio is reduced to 3.8:1, but the device remains ultra-wideband. Full article
(This article belongs to the Special Issue Electromagnetic Wave Absorbing Structures)
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Open AccessArticle
Quad-Band Plasmonic Perfect Absorber for Visible Light with a Patchwork of Silicon Nanorod Resonators
Materials 2018, 11(10), 1954; https://doi.org/10.3390/ma11101954
Received: 10 September 2018 / Revised: 26 September 2018 / Accepted: 10 October 2018 / Published: 12 October 2018
Cited by 4 | PDF Full-text (1514 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, a plasmonic perfect absorber (PPA) based on a silicon nanorod resonator (SNRR) for visible light is proposed and investigated numerically. The proposed PPA is only a two-layer nanostructure consisting of a SNRR periodic array and metal substrate. The perfect absorption [...] Read more.
In this paper, a plasmonic perfect absorber (PPA) based on a silicon nanorod resonator (SNRR) for visible light is proposed and investigated numerically. The proposed PPA is only a two-layer nanostructure consisting of a SNRR periodic array and metal substrate. The perfect absorption mainly originates from excitation of the localized surface plasmon resonance (LSPR) mode in the SNRR structure. The absorption properties of this design can be adjusted by varying the radius (r) and height (h) of the SNRR structure. What is more, the stronger quad-band absorption can be achieved by combing four different radius of the SNRR in one period as a super unit-cell. Numerical simulation indicates that the designed quad-band PPA can achieve the absorbance of 99.99%, 99.8%, 99.8%, and 92.2% at 433.5 THz, 456 THz, 482 THz, and 504.5 THz, respectively. Further simulations show that the proposed PPA is polarization-insensitive for both transverse electric (TE) and transverse magnetic (TM) modes. The proposed PPA can be a desirable candidate for some potential applications in detecting, sensing, and visible spectroscopy. Full article
(This article belongs to the Special Issue Electromagnetic Wave Absorbing Structures)
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Open AccessArticle
Transmission Attenuation Power Ratio Analysis of Flexible Electromagnetic Absorber Sheets Combined with a Metal Layer
Materials 2018, 11(9), 1612; https://doi.org/10.3390/ma11091612
Received: 27 July 2018 / Revised: 27 August 2018 / Accepted: 3 September 2018 / Published: 4 September 2018
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Abstract
Electromagnetic noise absorber sheets have become a solution for solving complex electromagnetic interference (EMI) problems due to their high magnetic losses. This contribution is focused on characterizing a novel structure that is based on an absorber film with a metal layer attached on [...] Read more.
Electromagnetic noise absorber sheets have become a solution for solving complex electromagnetic interference (EMI) problems due to their high magnetic losses. This contribution is focused on characterizing a novel structure that is based on an absorber film with a metal layer attached on its top side. Two different absorber compositions were combined with Al and Cu metal layers in order to study the improvement on the performance of these structures, depending on the complex permeability, absorber film thickness, and type of metal. The transmission attenuation power ratio of the absorber films is analyzed and compared to the performance of absorber and metal structures. The measurement procedure is carried out attaching the films into a microstrip line that has been designed based on IEC standard (IEC 62333-2). This test fixture is employed as a transmission line to simulate a general noise path. The performance of absorber composites to filter electromagnetic noise is evaluated through analyzing S21 and S11 parameters. This is carried out with the aim of finding out in which conditions the absorption loss is improved when a metal layer is attached. In addition, the possible re-radiation effect, due to the magnetic field that is generated by the eddy currents induced in the metal layer, is examined. Full article
(This article belongs to the Special Issue Electromagnetic Wave Absorbing Structures)
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Open AccessArticle
An Analytical Study of Electromagnetic Deep Penetration Conditions and Implications in Lossy Media through Inhomogeneous Waves
Materials 2018, 11(9), 1595; https://doi.org/10.3390/ma11091595
Received: 19 July 2018 / Revised: 22 August 2018 / Accepted: 27 August 2018 / Published: 3 September 2018
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Abstract
This paper illustrates how the penetration of electromagnetic waves in lossy media strongly depends on the waveform and not only on the media involved. In particular, the so-called inhomogeneous plane waves are compared against homogeneous plane waves illustrating how the first ones can [...] Read more.
This paper illustrates how the penetration of electromagnetic waves in lossy media strongly depends on the waveform and not only on the media involved. In particular, the so-called inhomogeneous plane waves are compared against homogeneous plane waves illustrating how the first ones can generate deep penetration effects. Moreover, the paper provides examples showing how such waves may be practically generated. The approach taken here is analytical and it concentrates on the deep penetration conditions obtained by means of incident inhomogeneous plane waves incoming from a lossless medium and impinging on a lossy medium. Both conditions and constraints that the waveforms need to possess to achieve deep penetration are analysed. Some results are finally validated through numerical computations. The theory presented here is of interest in view of a practical implementation of the deep penetration effect. Full article
(This article belongs to the Special Issue Electromagnetic Wave Absorbing Structures)
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Open AccessArticle
Structure and Electromagnetic Properties of Cellular Glassy Carbon Monoliths with Controlled Cell Size
Materials 2018, 11(5), 709; https://doi.org/10.3390/ma11050709
Received: 4 April 2018 / Revised: 24 April 2018 / Accepted: 28 April 2018 / Published: 1 May 2018
Cited by 1 | PDF Full-text (5964 KB) | HTML Full-text | XML Full-text
Abstract
Electromagnetic shielding is a topic of high importance for which lightweight materials are highly sought. Porous carbon materials can meet this goal, but their structure needs to be controlled as much as possible. In this work, cellular carbon monoliths of well-defined porosity and [...] Read more.
Electromagnetic shielding is a topic of high importance for which lightweight materials are highly sought. Porous carbon materials can meet this goal, but their structure needs to be controlled as much as possible. In this work, cellular carbon monoliths of well-defined porosity and cell size were prepared by a template method, using sacrificial paraffin spheres as the porogen and resorcinol-formaldehyde (RF) resin as the carbon precursor. Physicochemical studies were carried out for investigating the conversion of RF resin into carbon, and the final cellular monoliths were investigated in terms of elemental composition, total porosity, surface area, micropore volumes, and micro/macropore size distributions. Electrical and electromagnetic (EM) properties were investigated in the static regime and in the Ka-band, respectively. Due to the phenolic nature of the resin, the resultant carbon was glasslike, and the special preparation protocol that was used led to cellular materials whose cell size increased with density. The materials were shown to be relevant for EM shielding, and the relationships between those properties and the density/cell size of those cellular monoliths were elucidated. Full article
(This article belongs to the Special Issue Electromagnetic Wave Absorbing Structures)
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Open AccessArticle
Effect of Aspect Ratio on the Permittivity of Graphite Fiber in Microwave Heating
Materials 2018, 11(1), 169; https://doi.org/10.3390/ma11010169
Received: 21 November 2017 / Revised: 11 January 2018 / Accepted: 17 January 2018 / Published: 22 January 2018
Cited by 1 | PDF Full-text (3083 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Microwave (MW) heating has received attention as a new heating source for various industrial processes. Some materials are expected to be a more effective absorber of MW, and graphite is observed as a possible candidate for high-temperature application. We investigated the dependence of [...] Read more.
Microwave (MW) heating has received attention as a new heating source for various industrial processes. Some materials are expected to be a more effective absorber of MW, and graphite is observed as a possible candidate for high-temperature application. We investigated the dependence of the aspect ratio of graphite fibers on both their heating behavior and permittivity under a 2.45 GHz MW electric field. In these experiments, both loss tangent and MW heating behavior indicated that the MW absorption of conductive fibers increases with their aspect ratio. The MW absorption was found to be well accounted for by the application of a spheroidal model for a single fiber. The absorption of graphite fibers decreases with increasing aspect ratio when the long axis of the ellipsoid is perpendicular to the electric field, whereas it increases with the aspect ratio when the long axis is parallel to the electric field. The analytical model indicated that MW heating of the conductive fibers is expected to depend on both the shape and arrangement of the fibers in the electric field. Full article
(This article belongs to the Special Issue Electromagnetic Wave Absorbing Structures)
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Review

Jump to: Research

Open AccessReview
Advanced Radar Absorbing Ceramic-Based Materials for Multifunctional Applications in Space Environment
Materials 2018, 11(9), 1730; https://doi.org/10.3390/ma11091730
Received: 31 July 2018 / Revised: 7 September 2018 / Accepted: 12 September 2018 / Published: 14 September 2018
Cited by 1 | PDF Full-text (6242 KB) | HTML Full-text | XML Full-text
Abstract
In this review, some results of the experimental activity carried out by the authors on advanced composite materials for space applications are reported. Composites are widely employed in the aerospace industry thanks to their lightweight and advanced thermo-mechanical and electrical properties. A critical [...] Read more.
In this review, some results of the experimental activity carried out by the authors on advanced composite materials for space applications are reported. Composites are widely employed in the aerospace industry thanks to their lightweight and advanced thermo-mechanical and electrical properties. A critical issue to tackle using engineered materials for space activities is providing two or more specific functionalities by means of single items/components. In this scenario, carbon-based composites are believed to be ideal candidates for the forthcoming development of aerospace research and space missions, since a widespread variety of multi-functional structures are allowed by employing these materials. The research results described here suggest that hybrid ceramic/polymeric structures could be employed as spacecraft-specific subsystems in order to ensure extreme temperature withstanding and electromagnetic shielding behavior simultaneously. The morphological and thermo-mechanical analysis of carbon/carbon (C/C) three-dimensional (3D) shell prototypes is reported; then, the microwave characterization of multilayered carbon-filled micro-/nano-composite panels is described. Finally, the possibility of combining the C/C bulk with a carbon-reinforced skin in a synergic arrangement is discussed, with the aid of numerical and experimental analyses. Full article
(This article belongs to the Special Issue Electromagnetic Wave Absorbing Structures)
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