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Torres García, Alicia E.

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Torres García

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Alicia E.

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Ingeniería Eléctrica, Electrónica y de Comunicación

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0000-0001-7952-7910

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811111

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Now showing 1 - 10 of 17
  • PublicationOpen Access
    Ku band low profile asymmetric Bull’s-Eye antenna with reduced side lobes and monopole feeding
    (IEEE, 2018) Beaskoetxea Gartzia, Unai; Torres García, Alicia E.; Beruete Díaz, Miguel; Ingeniaritza Elektrikoa eta Elektronikoa; Institute of Smart Cities - ISC; Ingeniería Eléctrica y Electrónica; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
    In this paper, a linearly polarized low profile and asymmetric Bull’s-Eye leaky wave antenna fed by a monopole operating at 13 GHz is presented. Broadside radiation from the monopole is achieved by surrounding it with an asymmetric array of semicircular metallic strips on a grounded dielectric slab. With this implementation we demonstrate high gain with a weight of less than 80 g and lower side lobe levels compared to previous designs fed by a resonant slot. The measured antenna shows an experimental gain of 19.4 dBi with only 5 periods and a side lobe level of −16 dB (−20.3 dB for the numerical ideal case at f = 12.6 GHz), along with a narrow 6º beamwidth
  • PublicationOpen Access
    Enhancing the infrared and visible emission properties of calcium silicate hydrate for radiative cooling using metamaterials
    (IEEE, 2022) Lezaun Capdevila, Carlos; Dolado, J. 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.
  • PublicationOpen Access
    Comparison of modified Soret lenses for dual band integrated detectors
    (IEEE, 2020) Torres García, Alicia E.; Pérez Escudero, José Manuel; Gonzalo García, Ramón; Ederra Urzainqui, Íñigo; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
    This paper presents the comparison of different modified Soret lenses suitable for a millimeter and submillimeterwave dualband integrated pixel detectors. The approach is based on the modification of a printed planar Soret lens, designed to operate in the sub-mm range, to obtain an antenna at the millimeter region. Three modifications of a transmission-mode Soret Lens at 850 GHz based on spiral, logarithmic and meander antennas geometries have been analyzed with a combination of Kirchhoffs Diffraction and full-wave simulation methods. The performance of the designs has been experimentally demonstrated in the submillimeterwave band, showing good agreement with simulation results.
  • PublicationOpen Access
    Silicon integrated subharmonic mixer on a photonic-crystal platform
    (IEEE, 2021) Torres García, Alicia E.; Pérez Escudero, José Manuel; Teniente Vallinas, Jorge; Gonzalo García, Ramón; Ederra Urzainqui, Íñigo; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
    This paper presents a planar silicon integrated subharmonic mixer on top of a photonic-crystal platform. The local oscillator (LO) power is injected through a 2D photoniccrystal (PC) slab to a resonant cavity that effectively couples the signal to a planar bow-tie antenna. The same antenna, which is printed on the top of the PC cavity, contains an antiparallel Schottky diode pair which performs the down-conversion. The proposed design is a simple, easy to integrate, low cost, low profile device. Moreover, the described fabrication process is compatible with active components integration. The performance of the design has been experimentally demonstrated showing good agreement with the simulation and is comparable with the stateof-the-art of planar mixers. The work presented here is based on concepts and technologies from electronics and photonics domains and may be a good starting point for the creation of new devices, allowing the integration and upgrading of existing techniques from both worlds.
  • PublicationOpen Access
    Evolutionary algorithms applied to multi-layered radiative cooling metamaterials
    (IEEE, 2022) Lezaun Capdevila, Carlos; Jorajuria Gómez, Tania; Torres García, Alicia E.; Herrera, Pilar; Beruete Díaz, Miguel; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
    A newly design method for designing multi-layered radiative cooling metamaterials based on genetic algorithms (GAs) is exposed. The developed GA has been tested in three cases, resulting in three different structures that achieve, theoretically under direct sunlight, a net cooling power of 39.96 W/m 2 , 57.78 W/m 2 and 61.77 W/m 2 . Such devices are composed of 9, 15 and 24 layers respectively with a total thickness of less than 4.8 µm in the worst case. By the nature of the method, fewer design experience in metamaterials is needed, as well as it is free-cost, due to the use of analytical calculations for the emissivity of the meta materials instead of a commercial generic electromagnetic solver. Automated design of radiative cooling multi-layered structures and other applications in the infrared range can be further developed with this work.
  • PublicationOpen Access
    Metal-free design of a multilayered metamaterial with chirped Bragg grating for enhanced radiative cooling
    (Optica, 2023) Osuna Ruiz, David; Lezaun Capdevila, Carlos; Torres García, Alicia E.; Beruete Díaz, Miguel; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
    A wideband, all-dielectric metamaterial structure for enhancing radiative cooling is investigated. The structure is optimized to reflect most of the solar irradiance window (between 0.3 µm–3 µm), which is one of the biggest challenges in highly efficient radiative cooling coatings. The design is based on the principles of Bragg gratings, which constitutes a simple synthesis procedure to make a broadband reflector of reduced dimensions, without metallic layers, while keeping a flat enough response in the entire bandwidth. Numerical results show that reflection of solar irradiation can be easily tailored and maximized using this method, as well as the net cooling power of the device, about ∼79 W/m2 at daytime (about double at night-time) and a temperature reduction of 23 K (assuming no heat exchange) and 7 K assuming a heat exchange coefficient of 10 W/m2/K, for a device and ambient temperatures of 300 K and 303 K, respectively. This occurs even in detriment of absorption in the atmospheric window (8 µm–13 µm). Results also show the importance of efficiently reflecting solar irradiance for such technologies and its relevance in synthesis and design without using metallic components.
  • PublicationOpen Access
    A Chebyshev transformer-based microstri-to-groove-gap-waveguide inline transition for MMIC packaging
    (IEEE, 2019) Pérez Escudero, José Manuel; Torres García, Alicia E.; Gonzalo García, Ramón; Ederra Urzainqui, Íñigo; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
    The gap waveguide technology has become an alternative to millimeter- and submillimeter-wave electronic circuit packaging thanks to the loss reduction associated with its use. In this paper, a simplified design of an inline transition between a microstrip and a groove gap waveguide (GGW) operating at the W-band is presented. The transition consists of a tapered microstrip line and a Chebyshev adapter that couple the quasi-TEM mode of the microstrip line to the so-called vertical mode of the GGW. The simplicity of this design makes this transition appropriate for monolithic microwave integrated circuit (MMIC) packaging at millimeter frequencies and above. The simulation results have been experimentally validated in the W-band. A good performance has been achieved, resulting in a return loss better than 10 dB and a mean insertion loss lower than 2 dB.
  • PublicationOpen Access
    Design of a groove gap waveguide to microstrip inline transition
    (IEEE, 2019) Pérez Escudero, José Manuel; Torres García, Alicia E.; Gonzalo García, Ramón; Ederra Urzainqui, Íñigo; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
    In this paper the design of an inline transition between microstrip and groove gap waveguide operating at Wband is presented. The transition consists of two sections: a tapered microstrip line and a Chebyshev transformer. The simplicity of this design makes this transition appropriate for MMIC packaging at millimeter frequencies and above. Experimental validation has been carried out in theW-band. Good performance has been achieved: return loss better than 10 dB and mean insertion loss lower than 2 dB.
  • PublicationOpen Access
    Design of multi-layered radiative cooling structures using evolutionary algorithms
    (IEEE, 2022) Lezaun Capdevila, Carlos; Jorajuria Gómez, Tania; Torres García, Alicia E.; Herrera, Pilar; Beruete Díaz, Miguel; Institute of Smart Cities - ISC; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Gobierno de Navarra / Nafarroako Gobernua
    In this work we present a novel way to design thinfilm radiative cooling metamaterials based on genetic algorithms. Three simulations with different design constraints have been done, resulting in three structures that achieve 39.96 W/m2 , 57.78 W/m2 and 61.77 W/m2 under direct sunlight, respectively. These structures are shorter than 5 µm of height and are composed of 9, 15 and 24 layers. This design method has the advantages of being automatable, needs fewer design experience in metamaterials and does not rely on commercial simulators. This work opens the path to an easy way of automated design of thin-film multi-layered devices for radiative cooling and other applications in the infrared range.
  • PublicationOpen Access
    Nanoparticle derived suppressed-scattering bands for radiative cooling
    (IEEE, 2023) Lezaun Capdevila, Carlos; Pérez Escudero, José Manuel; Torres García, Alicia E.; Caggiano, Antonio; Peralta, Ignacio; Dolado, Jorge S.; Liberal Olleta, Íñigo; Beruete Díaz, Miguel; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
    Light scattering using resonant nanoparticles is crucial for improving sun irradiance reflection in a daytime radiative cooler. Popular nanoparticles in radiative cooling literature are analyzed in terms of scattering performance due to material dispersion. Different scattering properties in the infrared range have been detected while a similar behavior can be achieved in the solar range due to changes in material dispersion. Also, suppressed scattering windows are produced by dispersive nanoparticles, allowing high reflectance while enabling thermal emission selectively. Material dispersion alone produces such scattering windows, thus, given a material, they will always remain in the same region regardless geometry and location of particles. Lastly, calcium silicate hydrate (CSH), the main phase of concrete, is studied as a dispersive host example. These results demonstrate the importance of a co-design between host and nanoparticles dispersion for daytime radiative cooling and that nanoporosities design are a key ingredient that could allow concrete-based daytime radiative coolers.