Open Access
Mechanical 144GHz beam steering with all-metallic epsilon-near-zero lens antenna
(AIP Publishing, 2014) Pacheco-Peña, Víctor; Torres Landívar, Víctor; Orazbayev, Bakhtiyar; Beruete Díaz, Miguel; Navarro Cía, Miguel; Sorolla Ayza, Mario; Engheta, Nader; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
An all-metallic steerable beam antenna composed of an ε-near-zero (ENZ) metamaterial lens is experimentally demonstrated at 144 GHz (λ0 = 2.083 mm). The ENZ lens is realized by an array of narrow hollow rectangular waveguides working just near and above the cut-off of the TE10 mode. The lens focal arc on the xz-plane is initially estimated analytically as well as numerically and compared with experimental results demonstrating good agreement. Next, an open-ended waveguide is placed along the lens focal arc to evaluate the ENZ-lens antenna steerability. A gain scan loss below 3 dB is achieved for angles up to plus/minus 15º.
Open Access
Tunable beam steering enabled by graphene metamaterials
(Optical Society of America, 2016) Orazbayev, Bakhtiyar; Beruete Díaz, Miguel; Khromova, Irina; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
We demonstrate tunable mid-infrared (MIR) beam steering devices based on multilayer graphene-dielectric metamaterials. The effective refractive index of such metamaterials can be manipulated by changing the chemical potential of each graphene layer. This can arbitrarily tailor the spatial distribution of the phase of the transmitted beam, providing mechanisms for active beam steering. Three different beam steerer (BS) designs are discussed: a graded-index (GRIN) graphene-based metamaterial block, an array of metallic waveguides filled with graphene-dielectric metamaterial and an array of planar waveguides created in a graphene-dielectric metamaterial block with a specific spatial profile of graphene sheets doping. The performances of the BSs are numerically analyzed, showing the tunability of the proposed designs for a wide range of output angles (up to approximately 70°). The proposed graphene-based tunable beam steering can be used in tunable transmitter/receiver modules for infrared imaging and sensing.
Open Access
Liquid crystals in reconfigurable reflectarray antennas for sub-millimeter waves
(IEEE, 2024-08-21) Pérez Quintana, Dayan; Aguirre Gallego, Erik; Olariaga Jauregui, Eduardo; Kuznetsov, Sergei A.; Lapanik, Valeri I.; Sutormin, Vitaly S.; Zyryanov, Victor Ya; Marcotegui Iturmendi, José Antonio; Beruete Díaz, Miguel; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
Accelerated technological progress responds to the dynamic evolution of wireless communication systems, fueled by the advent of 5G, the emergence of 6G, and the pervasive integration of the IoT paradigm. Smart antennas play a pivotal role in this advancement, facilitating electronic beam steering to meet escalating demands for enhanced bandwidth and elevated operating frequencies. The spotlight shifts to reconfigurable reflectarray antennas, gaining prominence over conventional phased arrays. Notably, liquid crystals (LCs) emerge as a promising avenue for creating electronically reconfigurable/switchable reflectarrays, specifically tailored for short millimeter and terahertz waves. LCs, as a unique aggregate state combining solid and liquid features, address current technology limitations. Their uniaxial nature and the ability to manipulate molecule orientation enable effective fine-tuning of dielectric permittivity without drawbacks present in existing technologies.
Open Access
Full-space metasurface at millimeter-wave frequencies
(IEEE, 2023) Ruiz Fernández de Arcaya, María; Marzo Pérez, Asier; Beruete Díaz, Miguel; Institute of Smart Cities - ISC
Conventional metasurfaces provide control over the electromagnetic waves in a single working frequency operating either in transmission or reflection. Full-Space Metasurfaces (FSM) are an extension that allows operation at two different frequencies with independent functionalities in transmission and reflection. This paper presents a gradient index FSM device based on a 3-layered unit cell where the phase modulation is implemented following the Pancharatman-Berry (PB) principle. The device is designed to operate at millimeter waves, with the lowest frequency operating in reflection and the highest one in transmission. To check the structure performance, a metasurface was designed to provide beam steering in reflection at 49.4 GHz and an amplitude image hologram in transmission at 104 GHz.
Open Access
Reconfigurable millimeter-wave reflectarray based on low loss liquid crystals
(IEEE, 2024) Pérez Quintana, Dayan; Aguirre Gallego, Erik; Olariaga Jauregui, Eduardo; Kuznetsov, Sergei A.; Lapanik, Valeri I.; Sutormin, Vitaly S.; Zyryanov, Victor Ya; Marcotegui Iturmendi, José Antonio; Beruete Díaz, Miguel; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
This article reports on the development and evaluation of a reconfigurable millimeter-wave reflectarray (RA) based on liquid-crystal (LC) substrate operating in the D-band (105–125 GHz). The RA is composed of a high-impedance surface (HIS) with a meta-array of 33 × 29 patches on a 2-mm-thick quartz substrate, separated from the ground plane (GP) by a 40-µm-thick LC layer. A novel LC composition with low dielectric losses (<0.003) and high dielectric anisotropy (>1.3) has been developed for operation at millimeter waves. The results demonstrate a reflection phase tunability of 210◦ and low insertion losses of 2.5 dB. Furthermore, the device was demonstrated as a proof of concept for 1-D beam-steering applications, exhibiting an operational bandwidth of 12 GHz.