Torres Landívar, Víctor

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https://academica-e.unavarra.es/handle/2454/50091

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Torres Landívar

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Víctor

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Ingeniería Eléctrica y Electrónica

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1172807

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810391

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2011 - 20164
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Subject: Metamaterials ×

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Now showing 1 - 4 of 4
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    PublicationOpen Access
    Plasmonics and metamaterials at terahertz frequencies
    (2014) Torres Landívar, Víctor; Beruete Díaz, Miguel; Navarro Cía, Miguel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
    The research presented in this manuscript falls under the framework of metamaterials and plasmonics. It is mainly focused on applications at terahertz (THz) frequencies, a spectral band located between microwaves and infrared. Metamaterials are advanced materials able to synthesize electromagnetic properties hardly found in natural materials by means of engineering their meta-atoms. Metallic inclusions are commonly used in metamaterials design. At low frequency bands such as microwaves and millimeter-waves, metals behave fundamentally differently than at infrared and optics. Plasmonics sets the theory of the interaction processes between electromagnetic radiation and conduction electrons of metals at such high frequencies. The objective of this thesis is to devise, design, analyze and, whenever possible, experimentally realize and measure new metamaterials and plasmonics devices for free-space quasi-optical applications. Particularly, field concentrators in the form of advanced lenses and nanoantennas as well as advanced polarizing devices are targeted. The contributions presented here start from the specific theory of the field and the results are supported by numerical simulations, analytical calculations and/or measurements of real prototypes.
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    PublicationOpen Access
    Experimental demonstration of a millimeter-wave metallic ENZ lens based on the energy squeezing principle
    (IEEE, 2015) Torres Landívar, Víctor; Orazbayev, Bakhtiyar; Pacheco-Peña, Víctor; Teniente Vallinas, Jorge; Beruete Díaz, Miguel; Navarro Cía, Miguel; Sorolla Ayza, Mario; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
    The performance of an epsilon-near zero (ENZ) plano-concave lens is experimentally demonstrated and verified at the D-band of the millimeter-waves. The lens is comprised of an array of narrow metallic waveguides near cut-off frequency, which effectively behaves as an epsilon-near-zero medium at 144 GHz. A good matching with free space is achieved by exploiting the phenomenon of energy squeezing and a clear focus with a transmission enhancement of 15.9 dB is measured. The lens shows good radiation properties with a directivity of 17.6 dBi and low cross-polar components of -34 dB. All results are supported by numerical simulations.
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    PublicationOpen 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.
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    PublicationOpen Access
    Accurate circuit modeling of fishnet structures for negative-index-medium applications
    (IEEE, 2016) Torres Landívar, Víctor; Mesa, Francisco; Navarro Cía, Miguel; Rodríguez Berral, Raúl; Beruete Díaz, Miguel; Medina, Francisco; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
    Metallic plates with a two-dimensional (2D) periodic distribution of sub-wavelength apertures are known to exhibit extraordinary transmission of electromagnetic waves. Stacking two or more of such plates gives place to the so-called fishnet structures, which constitute a popular way of achieving an effective negative index medium at frequencies ranging from microwaves to optics. Unfortunately, a general wideband equivalent circuit has not yet been proposed to facilitate its understanding and design. This work presents this circuit model with closed-form expressions for the circuit elements, thus making it possible to obtain the electrical response for this class of structures in a very efficient way. This procedure is much faster than alternative numerical methods at the same time that it retains a high level of accuracy when compared with some other oversimplified models. The circuit model also provides a simple rationale as well as a good physical insight in order to explain the qualitative behavior of such structures, independently of the number of stacked layers.