Open Access
Impact of diffraction on terahertz compressed sensing single-pixel imaging
(IEEE, 2024) Ndagijimana, Adolphe; Ederra Urzainqui, Íñigo; Heredia Conde, Miguel; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza
Terahertz (THz) single-pixel imaging, through compressive sensing, enables sampling below Nyquist rates and bypasses the need for mechanical scanning and the limitation of availability of high-resolution cost-effective THz imaging array detectors off-the-shelf. This research investigates how diffraction phenomena affect THz single-pixel imaging and properties of sensing matrices, along with the sparse signal reconstruction process. We introduce a variety of strategies designed to mitigate the effects of diffraction, along with novel methods to counteract the disruptions caused by THz physics, thereby preserving the integrity of the original sensing matrix and improving signal recoverability. A comprehensive simulation study sheds light on the effects of diffraction on the sensing matrices and their impact on signal reconstruction. Our results highlight the importance of accurate diffraction minimization techniques and sophisticated modelling in enhancing THz imaging systems.
Open Access
Induction theorem analysis of resonant nanoparticles: design of a huygens source nanoparticle laser
(American Physical Society, 2014) Liberal Olleta, Íñigo; Ederra Urzainqui, Íñigo; Gonzalo García, Ramón; Ziolkowski, Richard W.; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
We propose an advanced formulation of standard antenna theory for the basic investigation and design of resonant nanoparticles. This methodology is based on transforming the original scattering problem into a radiation configuration by invoking the induction theorem. Then applying basic antenna theory principles, such as the suppression of any reactive power, the properties of the resonances are engineered. This nanoantenna approach has been validated by revisiting a number of well-known multilayered core-shell structures. It provides additional important physical insights into how the core-shell structures operate and it enables combinations of different resonant phenomena associated with them, e.g., plasmonic and high-ϵ resonances, in an intuitive manner. Its efficacy is demonstrated by designing a multilayered nanoparticle that achieves lasing with a maximum directivity in the forward direction and a null in the backward direction, i.e., a Huygens source nanoparticle laser.
Open Access
Advanced feeds for mm-wave antenna systems
(Springer, 2018) Teniente Vallinas, Jorge; Iriarte Galarregui, Juan Carlos; Ederra Urzainqui, Íñigo; Gonzalo García, Ramón; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
Millimeter-wave antenna systems have traditionally required high performance feeds in order to fulfill its stringent requirements. Therefore, this goal has been achieved by corrugated horns. However, in the last years new applications mainly in the communication systems have driven the use of other types of antenna feed with slightly reduced performance but simpler manufacturing at mm-wave and submm-wave frequencies with improvements in cost reduction. These advanced profiles are usually based in smooth waveguide advanced profiles. Besides, the chapter describes different feed configurations based on metamaterial structures and several examples of metamaterial based or inspired antennas are considered. Then, this chapter covers the different alternatives currently used for mm-wave antenna feed: corrugated horns, spline horns, and metamaterial horns. At the end of each section, it includes some research successful results.
Open Access
Quantum antenna arrays: the role of quantum interference on direction-dependent photon statistics
(American Physical Society, 2018) Liberal Olleta, Íñigo; Ederra Urzainqui, Íñigo; Ziolkowski, Richard W.; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
We investigate the role of quantum interference phenomena on the characteristics of the fields radiated by an array of quantum emitters. In analogy to, but distinct from, classical outcomes, we demonstrate that the array geometry empowers control over direction-dependent photon statistics of arbitrary order. Our formulation enables the recognition of configurations providing spatial correlations with no classical counterpart. For example, we identify a system in which the angular distribution of the average number of photons is independent of the number and position of the emitters, while its higher-order photon statistics exhibit a directional behavior. These results extend our understanding of the fields generated by ensembles of quantum emitters, with potential applications to nonclassical light sources.
Open Access
Comparison of a slotted SIW antenna covered with metasurface vs. a traditional array
(IEEE, 2022) Chocarro Álvarez, Javier; Pérez Escudero, José Manuel; Ederra Urzainqui, Íñigo; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
In this article we compare two solutions to improve the radiation pattern of a slotted Substrate Integrated Waveguide (SIW) antenna: use of an E-plane array and covering it with a metasurface (MTS). To this aim, we compare the changes in performance, radiation pattern and aperture efficiency. We will see the advantages that the metasurface has over the typical array.
Open Access
Design of a planar meta-surface based on dipoles and wires for antenna applications
(2006) Sáenz Sáinz, Elena; Gonzalo García, Ramón; Ederra Urzainqui, Íñigo; Maagt, Peter de; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this paper, the design of a planar meta-surface based on dipoles and wires is presented. The unit cell is formed by three independent layers, which contain two parallel dipoles and one wire. The behaviour of these elements have been analysed separately as an independent unit cell, i.e., the one dipole unit cell, the two dipoles unit cell and the two dipoles and wire unit cell, by means of the transmission response and the dispersion diagrams. For a normal incident plane wave with the E field parallel to the wires and the H field axial to the dipoles, the electric and magnetic responses are excited producing a pass band behaviour which exhibit negative refractive index. This cell has been used to create meta-surfaces for antenna applications. Two configurations have been analysed; the first one is a superstrate of a dipole antenna with the pass band tuned to the resonant frequency of the dipole. It has been observed that the power goes through the meta-surface and is radiated mainly in boresight direction, which increases the directivity up to 8 dBi and the aperture efficiency of the whole configuration. In the second case, a substrate with the stop band tuned to the pass band of the superstrate and the resonant frequency of the dipole has been added. A directivity higher than 9 dBi with a back radiation of -20 dBi have been obtained.
Open Access
Compact antennas in ridge gap waveguide with circular polarization
(IEEE, 2020) Pérez Quintana, Dayan; Ederra Urzainqui, Íñigo; Beruete Díaz, Miguel; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
In this paper, two compact antennas in Ridge Gap Waveguide (RGW) technology, working at 60 GHz, with a high-purity circular polarization (CP) within a broad bandwidth are manufactured and measured. The antennas are fed from the bottom plane with a WR-15 waveguide (V-band), which couples the wave to the RGW. CP is generated in a simple and effective way, by means of two orthogonal feeder arms that excite a CP in a diamond-shaped slot on top. A broadband matching with reflection coefficient magnitude below -10 dB (S-11 < -10 dB) is achieved from approximately 60.3 to 69.6 GHz (> 9 GHz). Applying the axial ratio criterion (AR < 3dB) the bandwidth in CP is 14.48%, with respect to the central frequency (59 to 70 GHz). The maximum gain in both designs is obtained at 67 GHz, with a value of 5.49 and 11.12 dB respectively.
Open Access
Enhancement of the power radiated by a dipole antenna at boresight by means of a left handed superstrate
(IEEE, 2006) Sáenz Sáinz, Elena; Ederra Urzainqui, Íñigo; Gonzalo García, Ramón; Maagt, Peter de; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this paper a comparison between the measured radiation performances of a single dipole and a dipole with a left handed superstrate based on a finite periodic repetition of a unit cell is presented. First of all the return losses and resonant frequency of the dipole has been measured for different sizes of the superstrate, having a good impedance matching and a decrease in the resonant frequency as the number of cells increase. By using an anechoic chamber and a receiver horn antenna, the power transmitted at boresight has been measured for different frequencies, observing a filtering behaviour due to the resonant characteristic of the superstrate and an improvement of the power transmitted at the resonant frequency of around 3 dB. Comparing the H and E plane radiation patterns of a dipole and the dipole with superstrate, more symmetrical and directive radiation patterns can be observed. Finally, a comparison between the simulated and measured aperture efficiency is presented with a good agreement.
Open Access
Dipolos y metamateriales: mejora de las características de radiación
(2004) Sáenz Sáinz, Elena; Gonzalo García, Ramón; Ederra Urzainqui, Íñigo; Maagt, Peter de; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this work, pass band properties of Left Handed Media (LHM) are demonstrated. These properties have been used in order to make a LHM super-substrate that is put over a dipole antenna. This super-substrate is going to determine the characteristics of radiation patterns. Simulation with different types of configurations are presented in order to enhance the features of radiation patterns at bore-sight direction.
Open Access
300 GHz optoelectronic transmitter combining integrated photonics and electronic multipliers for wireless communication
(MDPI, 2019) Ali, Muhsin; Pérez Escudero, José Manuel; Guzmán Martínez, Robinson Cruzoe; Lo, Mu Chieh; Ederra Urzainqui, Íñigo; Gonzalo García, Ramón; García Muñoz, Luis Enrique; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
THz communications systems at carrier frequencies above 200 GHz are the key to enable next-generation mobile communication networks with 100 Gbit/s wireless data rates. One of the key questions is, which carrier frequency generation technique will be the most suitable. This is currently addressed by two separate approaches, electronics-based and photonics-based. We present in this paper a truly microwave photonic approach that benefits from the main key features of each, bandwidth, tunability, stability and fiber compatibility from photonics and power handling capability from the electronics. It is based on a Photonic Local Oscillator (PLO), generating a 100 GHz frequency, fed into an electronic frequency multiplier. A high speed uni-travelling carrier photodiode (UTC-PD) provides the 100 GHz PLO for Schottky tripler diodes, generating 300 GHz signal. To feed the UTC-PD, we present a photonic integrated mode locked laser source. According to the simulations and measurements, the developed transmitter can produce a maximum of 12 μWof THz power at 280 GHz.