Open Access
Dielectric sensing of deeply subwavelength analytes using epsilon-near-zero waveguides
(IEEE, 2024-10-08) Lezaun Capdevila, Carlos; Pacheco-Peña, Víctor; Beruete Díaz, Miguel; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
The advent of metamaterials brought new wave-matter interaction paradigms to manipulate field and waves at will. Their applications are numerous: antennas, lenses, invisibility cloaking, computing, vortex beams and more. In turn, epsilon-near-zero (ENZ) metamaterials opened up new phenomena for light manipulation due to their exotic propagation constant, wavenumber and characteristic impedance. In 2008, it was demonstrated that a rectangular waveguide can emulate ENZ media by working near the cutoff frequency [1]. Moreover, the incredible field confinement inside the ENZ waveguide provided interesting features for sensing applications [2]. Our work further develops the idea of a dielectric body sensor based on a ENZ waveguide by considering an analyte partially filling the waveguide [3] and demonstrating empirically the setup [4].
Open Access
Electroinductive waves in chain of complementary metamaterial elements
(AIP Publishing, 2006) Beruete Díaz, Miguel; Falcone Lanas, Francisco; Freire, M. J.; Marqués, R.; Baena, J.D.; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
Electronductive waves supported by chains of resonators drilled on a metallic plate are presented. Propagation of energy comes as a consequence of the electric coupling between these resonators. Therefore, these waves are termed as electroinductive waves. They can be interpreted as the dual counterpart of the so-called magnetoinductive waves, which are due to the mutual inductances along chains of resonators. In order to show their existence, some electromagnetic simulations and experiments have been carried out, using as resonators the complementary particle of the split ring resonator. The reported result opens the way to a high variety of applications in one- and two-dimensional devices, such as transducers, delay lines, bends, power dividers, couplers, antennas, lenses, etc.
Open Access
Blind spot mitigation in phased array antenna using metamaterials
(IEEE, 2014) Crépin, Thomas; Martel, Cédric; Gabard, Benjamin; Boust, Fabrice; Martinaud, Jean-Paul; Dousset, Thierry; Rodríguez Ulibarri, Pablo; Beruete Díaz, Miguel; Loecker, Claudius; Bertuch, Thomas; Marcotegui Iturmendi, José Antonio; Maci, Stefano; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this work, a metaradome based on a fakir’s bed of nails is designed and tested in order to suppress the blind directions of a 100-element antenna array. The antenna is a microstrip array designed to operate in X-band. The fakir’s bed metamaterial-like was first approximated using analytical formulas before a full-wave numerical optimization. Experimental results are exposed and confronted to numerical results. They show a significant reduction of the blind spot subsequent to the metaradome addition.
Open Access
Super-oscillatory metalens at terahertz for enhanced focusing with reduced side lobes
(MDPI, 2018) Legaria Lerga, Santiago; Pacheco-Peña, Víctor; Beruete Díaz, Miguel; Institute of Smart Cities - ISC
In this paper, we design and numerically demonstrate an ultra-thin super-oscillatory metalens with a resolution below the diffraction limit. The zones of the lens are implemented using metasurface concepts with hexagonal unit cells. This way, the transparency and, hence, efficiency is optimized, compared to the conventional transparent–opaque zoning approach that introduces, inevitably, a high reflection in the opaque regions. Furthermore, a novel two-step optimization technique, based on evolutionary algorithms, is developed to reduce the side lobes and boost the intensity at the focus. After the design process, we demonstrate that the metalens is able to generate a focal spot of 0.46λ0 (1.4 times below the resolution limit) at the design focal length of 10λ0 with reduced side lobes (the side lobe level being approximately −11 dB). The metalens is optimized at 0.327 THz, and has been validated with numerical simulations.
Open Access
Compact pillbox reflector based on geodesic lens
(IEEE, 2022) Pérez Quintana, Dayan; Chen, Q.; Beruete Díaz, Miguel; Quevedo-Teruel, O.; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
We propose a pillbox antenna in combination with a geodesic lens at 60 GHz. The antenna is implemented in a dual-layer parallel plate waveguide. The waves from a geodesic lens in a first layer, after being reflected by a parabolic mirror connecting the rims of the two layers, enter a second layer and illuminate the radiation aperture. Since the lens produces a virtual focus, the reflector works as if it is fed from that a further location, making the system more compact.
Open Access
Experimental demonstration of deeply subwavelength dielectric sensing with epsilon-near-zero (ENZ) waveguides
(American Institute of Physics, 2022) Beruete Díaz, Miguel; Engheta, Nader; Pacheco-Peña, Víctor; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
In this Letter, an all metallic sensor based on ε-near-zero (ENZ) metamaterials is studied both numerically and experimentally when working at microwave frequencies. To emulate an ENZ medium, a sensor is made by using a narrow hollow rectangular waveguide, working near the cutoff frequency of its fundamental TE 10 mode. The performance of the sensor is systematically evaluated by placing subwavelength dielectric analytes (with different sizes and relative permittivities) within the ENZ waveguide and moving them along the propagation and transversal axes. It is experimentally demonstrated how this ENZ sensor is able to detect deeply subwavelength dielectric bodies of sizes up to 0.04λ and height 5 × 10 −3 λ with high sensitivities (and the figure of merit) up to 0.05 1/RIU (∼0.6 1/GHz) and 0.6 1/RIU when considering the sensor working as a frequency- or amplitude-shift-based device, respectively.
Open Access
Hyperbolic lens antenna in groove gap waveguide technology at sub-millimeter waves
(IEEE, 2022) Pérez Quintana, Dayan; Biurrun Quel, Carlos; Ederra Urzainqui, Íñigo; González-Ovejero, David; Beruete Díaz, Miguel; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
In this paper, a flat hyperbolic lens antenna using Groove Gap Waveguide (GGW) technology is designed at 300 GHz. A GGW horn antenna is used to feed the metamaterial lens placed in a parallel plate waveguide (PPW), in order to increase the directivity in the direction of propagation. The combination of both devices, the metalens and the GGW antenna, achieves excellent radiation performance.
Open Access
A slow light fishnet-like absorber in the millimeter-wave range
(EMW Publishing, 2011) Navarro Cía, Miguel; Torres Landívar, Víctor; Beruete Díaz, Miguel; Sorolla Ayza, Mario; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
A novel route to achieve a narrowband free-space electromagnetic absorber in any range of the spectrum based on stacked subwavelength hole arrays is proposed. The absorption is obtained by means of a slow light mode inside a fishnet-like engineered structure and exploiting the unavoidable misalignments and bucklings of the free-standing stack. An incoming pulse becomes permanently trapped in the structure due to the near zero group velocity which causes an enhancement of the radiation-structure interaction that leads to a huge increment of losses arising from the finite conductivity of the metal as well as arrangement tolerances. This approach is studied not only by simulation but also experimentally under normal incidence at millimeter wavelengths. Moreover, a basic grasp about the angular dependence of the structure is given by analyzing the 2D dispersion diagram. It shows that this scheme may also display high absorption under oblique incidence for s-polarization (or TE-polarization), whereas p-polarization (TM-polarization) would degrade its performance.
Open Access
Enhancing the infrared and visible emission properties of calcium silicate hydrate for radiative cooling using metamaterials
(IEEE, 2022) Lezaun Capdevila, Carlos; Dolado, Jorge S.; Torres García, Alicia E.; Pérez Escudero, José Manuel; Liberal Olleta, Íñigo; Beruete Díaz, Miguel; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
Two periodic structures composed of metal cylinders with different orientations are used to improve the solar reflection of calcium silicate hydrate (CSH) while maintaining its atmospheric emission. Interesting effects have been found when the distance between bars is small, suggesting that lattice effects, arising from the interaction between the rods could be leveraged in the design of these metamaterials. The size of the metal bars is selected based on state of the art micro-manufacturing techniques. This study limits its scope to a CSH gel model; i.e. the most important component of cement-based materials. Further research will be undertaken to consider a best description of the dielectric function of concrete.
Open Access
Nonbianisotropic complementary split ring resonators as angular selective metasurfaces
(Optical Society of America, 2017) Rodríguez Ulibarri, Pablo; Beruete Díaz, Miguel; Ingeniaritza Elektrikoa eta Elektronikoa; Institute of Smart Cities - ISC; Ingeniería Eléctrica y Electrónica
In this work, a metasurface with unconventional angular performance and composed by a nonbianisotropic complementary split ring resonator (NB-CSRR) is analyzed numerically and experimentally. A numerical study comparing the performance with the original complementary split ring resonator is conducted, showing very interesting transmission properties, such as complete filtering under normal incidence and high transmission peaks at oblique incidence for the NB-CSRR metasurface. A bilayered NB-CSRR prototype working at millimeter waves with a total thickness of 100 μm (0.1 times the operation wavelength) is fabricated and tested with a good agreement between simulation results and experiments. Very exciting applications based on the presented structure, such as advanced angular selectivity devices with great rejection levels at normal incidence and angular sensing devices, can be envisaged.