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• Compact Tunable negative Metamaterial for enhancing 5G network performance. • Frequency-Tunable Tri-Hexagon and Tri-Square Split Ring Resonator for Bandwidth Optimization. • Empowering 5G with Double Negative (DNG) Properties. • Fabrication of the proposed metamaterial experimental result to verify the overall performance. This paper introduces a compact tuneable metamaterial (MTM) unit cell featuring a tri-hexagon and tri-square split ring resonator (THTSSSR) structure designed for 5G communication applications. Metamaterials are employed to achieve unique electromagnetic properties not found in natural materials. The design process involves the arrangement of three square rings and three hexagon rings as metallic patches on a Rogers substrate (RT 5880), measuring 7 x 7 mm2 with a thickness of 1.575 mm. The proposed design exhibits double negative (DNG) properties, with resonances in the transmission coefficient (S21) at 3.493 GHz and a bandwidth of −10 dB covering frequencies between 3.057 and 3.711 GHz. Numerical simulations conducted using finite-integration techniques (FIT) in CST Microwave Studio validate the design's effectiveness, with confirmation through the Advanced Design System (ADS). The MTM unit cell demonstrates tuneable attributes, including negative permittivity ranging from 3.39 to 5 GHz and negative permeability from 3.39 to 3.86 GHz. These findings highlight the compactness and tunability of the proposed design, making it promising for 5G communication applications. [ABSTRACT FROM AUTHOR]

In a recent article (Yaqoob et al., 2021), Yaqoob et al. studied the tunable electromagnetic surface wave propagation on the graphene-covered left-handed material (LHM) slab backed by the perfect electric conductor (PEC). They derived the dispersion relations for both transverse electric (TE) and transverse magnetic (TM)-polarized surface waves, and then used the relations for two types of LHMs according to the spectral range, i.e., GHz- and THz-LHM. The present Comment points out although the system under consideration (i.e., graphene-covered LHM) is itself physically challenging, the results for THz-LHM are also rather unreal because the frequency regime to accomplish the calculations falls within the high THz frequency band. In such a frequency band, the conductor substrate no longer behaves like a PEC and thus the results are rather unreal when considering THz-LHM. We note that the metal, for example, gold or silver may be modeled as a PEC, but only for a few THz. Moreover, when considering GHz-LHM, we obtain new forms of dispersion relations for both TE and TM surface waves. We find that our dispersion relations do not agree with the results obtained by Yaqoob et al. [ABSTRACT FROM AUTHOR]

In this paper two novel left-handed composite metamaterials consisting of SRRs, wire and single sided S-shaped resonators are proposed. One of them is a reduced-size resonator which uses superposition hypothesis to achieve adjacent resonances for a much broader negative refraction passband. The other is a modified planar structure with improved electromagnetic coupling and reduced electrical size. Both structures are truly matched to free space in almost whole left-handed frequency band. It will be shown that these metamaterials are robust to the fabrication errors of misalignment printing on both sides of the substrate. The superior performance of these structures are investigated numerically and experimentally and compared with the other split ring resonators. Wedge shape simulation and experimental results confirm the left-handed passband. [ABSTRACT FROM AUTHOR]

We report on a new kind of planar left-handed metamaterial with both simulations and experiments in this article. Dual electric and magnetic resonance frequency bands are experimentally realized by introducing two different metallic elements in one unit cell, which offers a convenient approach in building dual-band or multiband negative-index metamaterials. The effective electromagnetic parameters obtained from the measured S-parameters indicate that negative refractive indexes are verified near 8.5 and 12 GHz with both negative permittivity and negative permeability. Field and current distribution at the dual resonances are also examined. At last, we calculated the radiated power of the magnetic dipole moments along y-axis. The idea can help us to fabricate dual-band or multiband metamaterial absorbers, filters, and antennas. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:493-497, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27399 [ABSTRACT FROM AUTHOR]

Abstract: As left-handed materials and metamaterials are becoming more prevalent, we examine the effect of negative permeability upon levitation force. We first consider two half spaces of differing permeability and a point magnetic source, so that the method of images may be employed. We determine that the resulting force may be larger than for conventional magnetic materials. We then illustrate the inclusion of a finite sample thickness. [Copyright &y& Elsevier]

Abstract: A kind of planar left-handed metamaterial (LHM) with unique configurations is demonstrated, which offers an approach in building dual-band negative-index materials. Simulated and experimental results predict two left-handed transmission bands near 11.1 and 14.6GHz. Dual bands of negative refractive indexes are verified using the retrieval procedure. Field and current distribution at the dual magnetic resonance are also examined. The effective electromagnetic parameters show that by carefully adjusting dimensions of the unit cell, electric and magnetic resonances can be coexistent at some frequency ranges with both negative permittivity and negative permeability. The idea can help us designing planar negative-index materials with multibands. [ABSTRACT FROM AUTHOR]

Abstract: We report our experimental results on two-dimensional left-handed metamaterials (LHM) exhibiting negative refraction and subwavelength imaging. Transmission and reflection spectra of LHM are studied and a left-handed transmission band is observed at the frequencies where both dielectric permittivity and magnetic permeability are negative. Impedance matching is verified both with the experiments and simulations. The two-dimensional LHM structure is verified to have a negative refractive index. We employed three different methods to observe negative refraction; refraction through prism-shaped LHM, beam shifting method, and phase shift experiments. We further demonstrated subwavelength imaging and resolution using LHM superlenses. The effect of thickness on the resolving power is investigated experimentally. [Copyright &y& Elsevier]

Abstract: We present here two examples of metamaterials for applications in the telecoms domain. The first concerns the realization of an ultra compact directive electronically reconfigurable antenna. The second deals with an infrared left-handed metamaterial working under normal incidence. For the first application, we use a composite phase varying metamaterial. An adjustable resonance radiating frequency between 7.9 and 8.2 GHz is obtained and a drastic enhancement in the directivity of the antenna is observed for a cavity thickness as small as (0.5 mm!). Concerning the second application we present simulations and measurements of a metamaterial made of gold wires and C-shaped nanostructures on silicon at infrared wavelengths. Both plasmonic resonances occur at 1.7 and 4.2 μm, corresponding to a simultaneously negative permittivity and permeability. A simplified version of this metamaterial is realized in the microwave domain. This new metamaterial is characterized and the left-handed behavior is experimentally demonstrated. To cite this article: B. Kante et al., C. R. Physique 9 (2008). [Copyright &y& Elsevier]

We will investigate the surface plasmon (SP) resonances of a dielectric-sandwiched metamaterial thin film. The parameters of the metamaterial are chose so that it has both negative $$\epsilon$$ and μ in visible frequency range. We use transfer matrix method to calculate the attenuated total reflection (ATR) spectra of the layered system to investigate the variation of SP resonances and the associated resonance strength. The results show that, for both p- and s-polarized incident lights, the plasmonic resonances can be manipulated by changing the thickness of the metamaterial. Otherwise, the plasmonic resonance strength for each SP mode can be tuned to become a maximum with proper slab thickness and light frequency for both polarized lights. [ABSTRACT FROM AUTHOR]

In this paper, we present a novel method to calculate the effective negative refractive index of a left-handed material (LHM)—a composite of split-ring resonators (SRRs) and thin wire structures. A LHM slab was first fabricated and then the measured transmission and reflection results were used to determine the LHM passband. To obtain the effective negative-refractive index, a microwave beam was obliquely launched to illuminate the slab for which a 2D spatial-field profile of the refracted beam outside the slab was obtained by scanning the lateral shifting of the field with respect to normal for a band of frequencies. A lateral shift of the refracted beam towards the same side of the incident beam for the LHM passband confirmed negative refraction in the LHM slab and the refractive index calculated for that frequency region was conclusively negative according to Snell's law. The presented method provides an alternate and efficient way to measure the effective refractive index of a LHM. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 593–596, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21417 [ABSTRACT FROM AUTHOR]

Abstract: Negative magnetic permeability of split ring resonator (SRR) is theoretically investigated in the visible light region. In our calculations, we considered the delay of the current inside the metal SRR in order to estimate the permeability of the SRR precisely. From the results, the silver SRR array with small capacitance exhibits negative permeability in all the visible range. The dependence of the permeability on the filling factor of the SRR elements is also discussed. [Copyright &y& Elsevier]

In this paper, we present an analysis of the dispersion properties for a left-handed material (LHM) using the 3D finite-difference time-domain (FDTD) method. We study the classic LHM structure composed of wire and split-ring resonators in a unit cell and calculate the resonant frequencies in order to produce the corresponding dispersion curve. The comparisons made between our numerical results and those previously published are in good agreement. In addition, through the incorporation of the Padé approximation with our FFT results, we reduce the computational time and enhance the results obtained. We anticipate that the development of such analysis tools for dispersion analysis will lead to an efficient way of characterizing LHMs and will facilitate the study of such metamaterial composites. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 394–397, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20833 [ABSTRACT FROM AUTHOR]

Backward-wave (BW) materials that have simultaneously negative real parts of their electric permittivity and magnetic permeability can support waves where phase and power propagation occur in opposite directions. These materials were predicted to have many unusual electromagnetic properties, among them amplification of the near-field of a point source, which could lead to the perfect reconstruction of the source field in an image [J. Pendry, Phys. Rev. Left. vol. 85, pg. 3966, 2000]. Often systems containing BW materials are simulated using the finite-difference time-domain technique. We show that this technique suffers from a numerical artifact due to its staggered grid that makes its use in simulations involving BW materials problematic. The pseudospectral time-domain technique, on the other hand, uses a collocated grid and is free of this artifact It is also shown that when modeling the dispersive BW material, the linear frequency approximation method introduces error that affects the frequency of vanishing reflection, while the auxiliary differential equation, the Z-transform, and the bilinear frequency approximation method produce vanishing reflection at the correct frequency. The case of vanishing reflection is of particular interest for field reconstruction in imaging applications. [ABSTRACT FROM AUTHOR]

Here, we analyze the transverse-magnetic (TM) wave interaction with a pair of slabs, one being an epsilon-negative (ENG) layer in which the real part of permittivity is assumed to be negative while its permeability has positive real part, and the other being a mu-negative (MNG) layer that has the real part of its permeability negative but its permittivity has positive real part. Although wave interaction with each slab by itself has predictable features, we show that the juxtaposition and pairing of such ENG and MNG slabs may, under certain conditions, lead to some unusual features, such as resonance, complete tunneling, zero reflection and transparency. The field distributions inside and outside such paired slabs are analyzed, and the Poynting vector distributions in such structures are studied. Using equivalent transmission-line models, we obtain the conditions for the resonance, complete tunneling and transparency, and we justify and explain the field behavior in these resonant paired structures. Salient features of the tunneling conditions, such as the roles of material parameters, slab thicknesses, dissipation, and angle of incidence are discussed. The analogy and correspondence between the ENG-MNG pair and the pair of a slab of conventional material juxtaposed with a "double-negative" medium is also discussed. Finally, a conceptual idea for a potential application of such a "matched" lossless ENG-MNG pair in "ideal" image displacement and image reconstruction is proposed. [ABSTRACT FROM AUTHOR]

We report the effective complex permittivity and permeability of 1D planar left-handed transmission-line metamaterials. These metamaterials are formed on coplanar waveguide (CPW) with simultaneous load of series-capacitive and shunt-inductive elements in periodic intervals. By employing our self-calibrated method of moments (MoM), the effective permittivity and permeability of these 1D metamaterials are numerically derived to illustrate the propagating and evanescent guided-wave behaviors over a microwave frequency range. We demonstrate that, in a certain frequency band, the permittivity and permeability simultaneously become negative with zero imaginary parts, and the transmission phase of a finite-extent CPW metamaterial becomes negative, as exhibited by both simulation and measurement. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1050–1052, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21597 [ABSTRACT FROM AUTHOR]

We report free space, microwave measurements with varying incidence angle on a material that exhibits a negative index of refraction. The experiments measure the index of refraction directly, for normal incidence, on prisms with three different apex angles. Snell's Law and the measured index are then used to verify refraction for off-normal incidence. The metamaterials used to construct the prisms are comprised of parallel metallic layers of posts and either "Greek key" spiral or split ring resonators. Despite this highly anisotropic composition, the measured refractive index was found to be nearly constant for exit angles up to 52° off the normal to the prism hypotenuse. In addition to being the first free space experimental verification of Snell's Law off the optical axis for this type of metamaterial, the measurements prove that the common parallel plate structures of negative index metamaterials are not acting as guided wave media. [ABSTRACT FROM PUBLISHER]