Open Access
Suppressing open stopband for terahertz periodic microstrip leaky-wave antennas
(IEEE, 2023) Haddad, Thomas; Biurrun Quel, Carlos; Lu, Peng; Kaya, Hacer; Mohammad, Israa; Stöhr, Andreas; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
This paper reports on a periodic microstrip Leaky-wave antenna (LWA). The open stopband issue is suppressed by altering the unit cell using a matching stub. The developed LWA is based on a grounded InP-substrate of 50 µm and has been fabricated and characterized between 0.23 to 0.33 THz. The dispersion diagram of the designed unit cell shows enhancement of the attenuation constant at the broadside frequency of 0.273 THz and about 50% less deflection at the broadside region on the Bloch impedance curves, consequently better impedance matching at the input. The simulated scattering parameters of the proposed LWA show that the return loss S11 is below 17 dB except for the broadside, which has a value of 13.8 dB. Furthermore, the beam steering capabilities of the antenna are simulated in the WR3.4 band and confirmed experimentally between 0.26 and 0.33 THz proving the beam direction to steer from −12° to +33°, respectively.
Open Access
Photonic-assisted 2-D terahertz beam steering enabled by a LWA array monolithically integrated with a BFN
(Optica, 2022) Haddad, Thomas; Biurrun Quel, Carlos; Lu, Peng; Tebart, Jonas; Sievert, Benedikt; Makhlouf, Sumer; Grzeslo, Marcel; Teniente Vallinas, Jorge; Río Bocio, Carlos del; Stöhr, Andreas; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
A novel photonic-assisted 2-D Terahertz beam steering chip using only two tuning elements is presented. The chip is based on an array of three leaky wave antennas (LWAs) with a monolithically integrated beamforming network (BFN) on a 50 µm-thick indium phosphide substrate. The THz beam angle in elevation (E-plane) is controlled via optical frequency tuning using a tunable dual-wavelength laser. An optical delay line is used for azimuth (H-plane) beam control. The simulated beam scanning range is 92° in elevation for a frequency sweep from 0.23 THz to 0.33 THz and 69.18° in azimuth for a time delay of 3.6 ps. For the frequency range from 0.26 THz to 0.32 THz, it is confirmed experimentally that the THz beam scans from −12° to +33°, which is in good agreement with the numerical simulations. The beam direction in azimuth scans with a total angle of 39° when applying a delay difference of 1.68 ps. A good agreement is found between theoretically predicted and experimentally determined THz beam angles with a maximum angle deviation below 5°. The experimental scanning angles are limited due to the mechanical constraints of the on-wafer probes, the on-chip integrated transition and the bandwidth of the THz receiver LNA. The mechanical limitation will be overcome when using a packaged chip.
Open Access
Multi-channel feedarray reflector antenna based radar concept for HRWS SAR imaging
(IEEE, 2021) Castillo, Javier del; Orgaz, Lara; García, Quiterio; Memeletzoglou, Nafsika; Toso, Giovanni; Imbembo, Ernesto; Biurrun Quel, Carlos; Río Bocio, Carlos del; Institute of Smart Cities - ISC
Large deployable reflector based multi-channel antenna systems are a key component of next generation SAR missions as they allow implementing multi-beam imaging capabilities and provide an efficient way to overcome the classical SAR resolution-coverage trade-off, covering wide swaths with high azimuth resolution. The presented work shows the design of a multichannel L-band SAR system and antenna architecture based on different feeders concepts and capable to map 400 km ground swath with 5 meter spatial resolution in dual polarization. The paper describes a preliminary design and architecture of the SAR system and the antenna where different design aspects including beamforming concepts and feedarray implementation techniques have been identified and assessed in view of achieving the required SAR performances while reducing the overall complexity of the solution.
Open Access
Noise in coherently radiating periodic structures beam forming networks
(IEEE, 2022) Biurrun Quel, Carlos; Río Bocio, Carlos del; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
Following the noise wave theory, beam forming networks based on Coherently Radiating Periodic Structures (CORPS-BFN) are analysed and proven to be capable of enhancing the Signal to Noise Ratio of the system by analogically multiplexing the signal and noise contributions present at every input port. The geometry of the network determines the maximum enhancement achievable, which is demonstrated to be independent from insertion losses. These findings are supported by a mathematical approach, as well as with experimental data.
Open Access
Design and characterization of terahertz CORPS beam forming networks
(Springer, 2023) Biurrun Quel, Carlos; Haddad, Thomas; Sievert, Benedikt; Kress, Robin; Weimann, Nils; Erni, Daniel; Rennings, Andreas; Stöhr, Andreas; Teniente Vallinas, Jorge; Río Bocio, Carlos del; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
This work reviews the design and applicability of beam-forming networks based on Coherently Radiating Periodic Structures (CORPS-BFN) at Terahertz (THz) frequency bands. These versatile networks offer two operation modes: a continuous beam steering – feeding an antenna array with a linearly progressive phase distribution – using a reduced number of phase controls; or a multi-beam operation, generating independent, overlapped beams. These networks are built upon the concatenation of power combiners/dividers (PCDs) with isolated outputs. The isolation is provided by monolithically integrated resistors, implemented with Ti/TiO thin films for the first time. In this work, a planar prototype of a (inputs/outputs) microstrip CORPS-BFN for operation in the WR3.4/WM-864 band (220–330 GHz) on a thin 50 m Indium Phosphide (InP) substrate is designed, fabricated, and characterized. The measured S-parameters show a reflection coefficient better than -15 dB and an insertion loss between 1.6 and 3.2 dB in the whole band. In addition, an isolation better than 20 dB between the input ports has been measured. An overall remarkable agreement is observed between the measurements and the simulations. Last, the applications, scalability and efficiency of this type of networks at the targeted band are discussed in detail.
Open Access
New hexagonal CORPS-BFN for multibeam antenna applications
(IEEE, 2020) Biurrun Quel, Carlos; Montesano, Antonio; Ederra Urzainqui, Íñigo; Iriarte Galarregui, Juan Carlos; Río Bocio, Carlos del; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
This work presents a new topology of a Coherently Radiating Periodic Structure - Beam Forming Network (CORPS-BFN) and its application for multibeam systems. A unit cell, consisting of a transition from a coaxial input to an intersection of three strip-lines with an angular span of 120 degrees, is proposed and analysed. A periodical replication of the cell gives rise to a uniform layer, allowing a proper matching of the ports of the network. Stacked layers allow in-phase propagation and distribution of the energy through the structure, increasing the number of output ports with each layer.
Open Access
Feeder system design for OLAF SAR instrument
(IEEE, 2022-04-11) Biurrun Quel, Carlos; García-García, Quiterio; Río Bocio, Carlos del; Institute of Smart Cities - ISC
The design of the feeding system for the focal array in OLAF (Over-Lapped Sub-Array Fed) antenna for SAR Instrument at L-Band is presented. The proposed design consists of a circular patch with a balanced excitation all of it embedded in a ground plane which is connected to the lower ground plane by some shorting pins, reducing the mutual coupling with the neighbour radiating elements of the focal array. The balanced excitation has been implemented with a 180° hybrid using the differential input port. Dual polarization is achieved by using two 180° hybrids within the same layer. The stringent requirements for the system, namely low in cross-polarization, high isolation between the two polarizations (both below the-25dB reference level) and azimuthal symmetry of the radiation pattern are fulfilled within all the working bandwidth.
Open Access
Hybrid analog-digital SAR instrument with reflector antenna and overlapped subarray feed for earth observation
(IEEE, 2021) García, Quiterio; Orgaz, Lara; Castillo, Javier del; Toso, Giovanni; Imbembo, Ernesto; Biurrun Quel, Carlos; Río Bocio, Carlos del; Memeletzoglou, Nafsika; Institute of Smart Cities - ISC
As part of the European Space Agency (ESA) studies of new instrument for Earth observation, the design of a synthetic aperture radar (SAR) architecture based on overlapped array antennas was launched last year. The objective of the activity is to develop a test unit of a reflector based SAR antenna fed by an array organized in overlapped subarrays, supporting novel multichannel wide-swath SAR architectures, and exploiting multiple beams in both azimuth and range/elevation directions. In the letter, a hybrid analog/digital beamforming on reception with analog beamforming approach on transmission is analyzed. The antenna system consists of a large oversize reflector with a feedarray capable of generating multiple beams on receive for digital processing. In the letter, a description of the hybrid SAR Instrument is presented, describing the characteristics of the system, the antenna, the considered feedarray options and the main characteristics and system performances.
Open Access
Impedance modelling for high frequency unitraveling-carrier photodiodes
(IEEE, 2021) Grzeslo, Marcel; Biurrun Quel, Carlos; Stöhr, Andreas; Institute of Smart Cities - ISC
High-speed photodiodes stand out as potential candidates to enable next-generation communication systems working as mmWave/THz sources due to their intrinsic broadband behaviour. Impedance matching is an essential task in microwave engineering that enables an efficient delivery of the power generated by the source (i.e. photodiode) to the load (i.e. antenna). In this work, we analyse the impedance of a generic uni-travelling carrier photodiode and its dependency with frequency, bias voltage and other operational parameters. In addition, we present some calculations and use cases, highlighting the importance of properly matching this impedance in an actual system.
Open Access
Connection of the SUMO microscopic traffic simulator and the unity 3D game engine to evaluate V2X communication-based systems
(MDPI, 2018) Olaverri Monreal, Cristina; Errea-Moreno Javier; Díaz-Álvarez, Alberto; Biurrun Quel, Carlos; Serrano Arriezu, Luis Javier; Kuba, Markus; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
In-vehicle applications that are based on Vehicle-to-Everything (V2X) communication technologies need to be evaluated under lab-controlled conditions before performing field tests. The need for a tailored platform to perform specific research on the cooperative Advanced Driving Assistance System (ADAS) to assess the effect on driver behavior and driving performance motivated the development of a driver-centric traffic simulator that is built over a 3D graphics engine. The engine creates a driving situation as it communicates with a traffic simulator as a means to simulate real-life traffic scenarios. The TraCI as a Service (TraaS) library was implemented to perform the interaction between the driver-controlled vehicle and the Simulation of Urban MObility (SUMO). An extension of a previous version, this work improves simulation performance and realism by reducing computational demand and integrating a tailored scenario with the ADAS to be tested. The usability of the implemented simulation platform was evaluated by means of an experiment related to the efficiency of a Traffic Light Assistant (TLA), showing the analysis of the answer that 80% of the participants were satisfied with the simulator and the TLA system implemented.