Special Issue "Higher Symmetries and Its Application in Microwave Technology, Antennas and Metamaterials"

A special issue of Symmetry (ISSN 2073-8994). This special issue belongs to the section "Physics and Symmetry/Asymmetry".

Deadline for manuscript submissions: closed (15 March 2019) | Viewed by 11857

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Special Issue Editors

Prof. Guido Valerio
E-Mail Website
Guest Editor
Sorbonne Université, Laboratoire d’Électronique et Électromagnétisme, 75252 Paris, France
Interests: antennas and propagation; periodic structures and metamaterials; higher symmetries; numerical methods, analytical modeling; leaky-waves; multilayered media
Prof. Dr. Oscar Quevedo-Teruel
E-Mail Website
Guest Editor
KTH Royal Institute of Technology
Interests: metasurfaces; lens antennas; geodesic lens; higher symmetries; transformation optics
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Special Issue Information

Dear Colleagues,

Artificial materials and surfaces are widely used in leaky-waves, holographic surfaces, band-gap materials, and graded-index flat lenses. However, their practical implementations are usually limited in terms of bandwidth, losses, fabrication precision, and input-matching. Approaches overcoming these limitations have recently been proposed through the implementation, or the breaking, of specific higher symmetries in each cell of the periodic medium. Spatial symmetries involve glide or twist symmetry, while an example of spatio-temporal symmetries is the parity-time symmetry.

Ultra-wide behaviors, large stop bands, wave propagation robust to defects and deformations are among the effects that can be achieved with these symmetries. They can lead to the novel generation of lenses, gap waveguides and filters with applications at millimeter-waves and higher frequencies: next-generation communication terminals, satellite communications, radio-astronomy, etc.

Prof. Guido Valerio
Prof. Dr. Oscar Quevedo-Teruel
Guest Editors

Manuscript Submission Information

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Keywords

  • Glide
  • Twist
  • Lenses
  • Antennas
  • Photonics
  • Metamaterials
  • Metasurfaces
  • Microwave
  • Electromagnetic band-gap
  • Dispersive analyses

Published Papers (7 papers)

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Research

Article
Modeling of Glide-Symmetric Dielectric Structures
Symmetry 2019, 11(6), 805; https://doi.org/10.3390/sym11060805 - 18 Jun 2019
Cited by 9 | Viewed by 1002
Abstract
Recently, there has been an increased interest in exploring periodic structures having higher symmetry properties, primarily based on metallic realization. The design of dielectric glide-symmetric structures has many challenges, and this paper presents a systematic analysis approach based on Floquet mode decomposition and [...] Read more.
Recently, there has been an increased interest in exploring periodic structures having higher symmetry properties, primarily based on metallic realization. The design of dielectric glide-symmetric structures has many challenges, and this paper presents a systematic analysis approach based on Floquet mode decomposition and mode matching technique. The presented procedure connects the analysis of standard periodic structures and glide-symmetric realizations, thus giving insight into the wave propagation and interaction characteristics. The obtained results were verified in comparison with results from known references and using a commercial solver, proving that the proposed analysis technique is inherently accurate, and the degree of accuracy depends only on the number of modes used. The proposed analysis approach represents the first step in the design process of dielectric periodic structures with glide symmetry. Full article
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Article
Bloch Analysis of Electromagnetic Waves in Twist-Symmetric Lines
Symmetry 2019, 11(5), 620; https://doi.org/10.3390/sym11050620 - 03 May 2019
Cited by 14 | Viewed by 1499
Abstract
We discuss here under which conditions a periodic line with a twist-symmetric shape can be replaced by an equivalent non-twist symmetric structure having the same dispersive behavior. To this aim, we explain the effect of twist symmetry in terms of coupling among adjacent [...] Read more.
We discuss here under which conditions a periodic line with a twist-symmetric shape can be replaced by an equivalent non-twist symmetric structure having the same dispersive behavior. To this aim, we explain the effect of twist symmetry in terms of coupling among adjacent cells through higher-order waveguide modes. We use several waveguide modes to accurately derive the dispersion diagram of a line through a multimodal transmission matrix. With this method, we can calculate both the phase and attenuation constants of Bloch modes, both in shielded and open structures. In addition, we use the higher symmetry of these structures to further reduce the computational cost by restricting the analysis to a subunit cell of the structure instead of the entire unit cell. We confirm the validity of our analysis by comparing our results with those of a commercial software. Full article
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Article
Analysis of Periodic Structures Made of Pins Inside a Parallel Plate Waveguide
Symmetry 2019, 11(4), 582; https://doi.org/10.3390/sym11040582 - 22 Apr 2019
Cited by 11 | Viewed by 1965
Abstract
In this work, we have analyzed different versions of periodic structures made with metallic pins located inside a parallel plate waveguide (PPWG), varying the symmetry and disposition of the pins. The analysis focuses on two main parameters related to wave propagation. On one [...] Read more.
In this work, we have analyzed different versions of periodic structures made with metallic pins located inside a parallel plate waveguide (PPWG), varying the symmetry and disposition of the pins. The analysis focuses on two main parameters related to wave propagation. On one hand, we have studied how the different proposed structures can create a stopband so that the parallel plate modes can be used in gap waveguide technology or filtering structures. On the other hand, we have analyzed the dispersion and equivalent refractive index of the first propagating transverse electromagnetic mode (TEM). The results show how the use of complex structures made with pins in the top and bottom plates of a PPWG have no advantages in terms of the achieved stopband size. However, for the case of the propagating mode, it is possible to find less dispersive modes and a higher range of equivalent refractive indices when using double-pin structures compared to a reference case with single pins. Full article
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Article
Fully Metallic Flat Lens Based on Locally Twist-Symmetric Array of Complementary Split-Ring Resonators
Symmetry 2019, 11(4), 581; https://doi.org/10.3390/sym11040581 - 22 Apr 2019
Cited by 12 | Viewed by 1759
Abstract
In this article, we demonstrate how twist symmetries can be employed in the design of flat lenses. A lens design is proposed, consisting of 13 perforated metallic sheets separated by an air gap. The perforation in the metal is a two-dimensional array of [...] Read more.
In this article, we demonstrate how twist symmetries can be employed in the design of flat lenses. A lens design is proposed, consisting of 13 perforated metallic sheets separated by an air gap. The perforation in the metal is a two-dimensional array of complementary split-ring resonators. In this specific design, the twist symmetry is local, as it is only applied to the unit cell of the array. Moreover, the twist symmetry is an approximation, as it is only applied to part of the unit cell. First, we demonstrate that, by varying the order of twist symmetry, the phase delay experienced by a wave propagating through the array can be accurately controlled. Secondly, a lens is designed by tailoring the unit cells throughout the aperture of the lens in order to obtain the desired phase delay. Simulation and measurement results demonstrate that the lens successfully transforms a spherical wave emanating from the focal point into a plane wave at the opposite side of the lens. The demonstrated concepts find application in future wireless communication networks where fully-metallic directive antennas are desired. Full article
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Article
One-Plane Glide-Symmetric Holey Structures for Stop-Band and Refraction Index Reconfiguration
Symmetry 2019, 11(4), 495; https://doi.org/10.3390/sym11040495 - 04 Apr 2019
Cited by 11 | Viewed by 1576
Abstract
This work presents a new configuration to create glide-symmetric structures in a single plane, which facilitates fabrication and avoids alignment problems in the assembly process compared to traditional glide-symmetric structures based on several planes. The proposed structures can be printed on the metal [...] Read more.
This work presents a new configuration to create glide-symmetric structures in a single plane, which facilitates fabrication and avoids alignment problems in the assembly process compared to traditional glide-symmetric structures based on several planes. The proposed structures can be printed on the metal face of a dielectric substrate, which acts as a support. The article includes a parametric study based on dispersion diagrams on the appearance of stop-bands and phase-shifting by breaking the symmetry. In addition, a procedure to regenerate symmetry is proposed that may be useful for reconfigurable devices. Finally, the measured and simulated S parameters of 10 × 10 unit-cell structures are presented to illustrate the attenuation in these stop-bands and the refractive index of the propagation modes. The attenuation obtained is greater than 30 dB in the stop-band for the symmetry-broken prototype. Full article
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Article
Time-reversal Symmetry in Antenna Theory
Symmetry 2019, 11(4), 486; https://doi.org/10.3390/sym11040486 - 04 Apr 2019
Cited by 7 | Viewed by 1353
Abstract
Here, I discuss some implications of the time-reversal invariance of lossless radiating systems. I highlight that time-reversal symmetry provides a rather intuitive explanation for the conditions of polarization and impedance matching of a receiving antenna. Furthermore, I describe a solution to generate the [...] Read more.
Here, I discuss some implications of the time-reversal invariance of lossless radiating systems. I highlight that time-reversal symmetry provides a rather intuitive explanation for the conditions of polarization and impedance matching of a receiving antenna. Furthermore, I describe a solution to generate the time-reversed electromagnetic field through the illumination of a matched receiving antenna with a Herglotz wave. Full article
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Article
Twist and Glide Symmetries for Helix Antenna Design and Miniaturization
Symmetry 2019, 11(3), 349; https://doi.org/10.3390/sym11030349 - 08 Mar 2019
Cited by 17 | Viewed by 2128
Abstract
Here we propose the use of twist and glide symmetries to increase the equivalent refractive index in a helical guiding structure. Twist- and glide-symmetrical distributions are created with corrugations placed at both sides of a helical strip. Combined twist-and glide-symmetrical helical unit cells [...] Read more.
Here we propose the use of twist and glide symmetries to increase the equivalent refractive index in a helical guiding structure. Twist- and glide-symmetrical distributions are created with corrugations placed at both sides of a helical strip. Combined twist-and glide-symmetrical helical unit cells are studied in terms of their constituent parameters. The increase of the propagation constant is mainly controlled by the length of the corrugations. In our proposed helix antenna, twist and glide symmetry cells are used to reduce significantly the operational frequency compared with conventional helix antenna. Equivalently, for a given frequency of operation, the dimensions of helix are reduced with the use of higher symmetries. The theoretical results obtained for our proposed helical structure based on higher symmetries show a reduction of 42.2% in the antenna size maintaining a similar antenna performance when compared to conventional helix antennas. Full article
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