Programa del congreso

An omnidirectional conformal array antenna has been implemented in air-filled waveguide technology for the 37-40 GHz band. The input port of the antenna is implemented by a standard WR28 rectangular waveguide. The TE10 mode excited in the rectangular waveguide is used to generate the TE01 mode inside a circular waveguide by a TE10-TE01 mode converter. The circular waveguide path is progressively expanded forming a radial waveguide structure, where the TE01 mode is also expanded and radially propagated by several radiating apertures. Due to the radial symmetry of the structure, an omnidirectional radiating performance with low ripple can be achieved. This structure has been 3D manufactured using the direct metal laser sintering technology. It has been measured in order to experimentally validate its performance. A very good agreement between simulations and measurements, a reflection coefficient below -10 dB, a low ripple omnidirectional performance in a conical cutting plane, a very low cross-polar radiation as well as a total efficiency higher than 73% are obtained. This conformal antenna design is proposed for 5G New Radio indoor applications.

In this communication, a half-mode waveguide based on Gap Waveguide technology for rapid prototyping is presented. A power divider is designed for demostration purposes. The power divider is constructed from two non-contacting metal pieces. The horizontally-polarized power divider is housed in the bottom piece. The height of the groove is about half that which would be required to propagate the fundamental mode. The top cover is a uniform pinned surface that acts as a High Impedance Surface (HIS) over the groove of the bottom plate. The simulated reflection coefficient shows values of less than -15 dB in the bandwidth of interest (28 to 31 GHz). This design stands out for its ease of fabrication and opens a horizon for cheaper and more robust GW designs for mass production.

This contribution presents the characterization of a stripline embedded in a coaxial system. The stripline has been manufactured using HIPS as the main substrate. The metallic strip has been manufactured on 50mm thick kapton film which is binded to the main substrate. The transmission line plays a very important role in the overall performance of the ultrawideband radiating element currently under development. A multiline method has been used for the characterization of

the stripline. The influence of the conductivity obtain in the fabrication of the conductive ink on the propagation characteristics of the transmission line is analyzed. Simulations and measurements assess the goodness and possible negative effects of the fabrication process to rely on it for future designs.

The design, manufacturing and characterization of

a Ku-band orthomode transducer (OMT) is presented in this

paper. The OMT topology uses a T-junction with a circular waveguide

body, two rectangular waveguides attached to the main

cylinder and having fundamental modes with different boundary

conditions at the symmetry plane. The short-circuited bottom of

the cylinder includes simple matching elements optimized along

the rest of the OMT for easing the manufacturing by Selective

Laser Melting (SLM) in a single block. The restrictions imposed

by this type of additive manufacturing are included in the design

process, to provide a structure with performance suitable for

satellite applications. A Ku-band prototype in the frequency

band 13.4 - 15.6 GHz is tested, obtaining return loss better

than 20 dB in this 15.2% band, with isolation of at least 45

dB between orthogonal polarizations. In addition, the results for

the insertion loss are better than 0.18 dB, showing the potential

of SLM in structures traditionally requiring spark erosion or

high-accuracy milling. The OMT has ben also characterized in

radiation, confirming the good experimental results.

This contribution describes the design process of a flat polarizer reflectarray antenna in Ka-band for high data throughput from nanosatellites. The reflectarray has been designed to focus a high-gain beam while converting the incident polarization from dual-linear polarization into dual-circular. The flat surface of the reflectarray simplifies the mounting of the antenna on the small spacecraft and the linear-to-circular polarization conversion allows to reduce the number of components in the feed chain, also reducing the cost and complexity of the antenna subsystem. A 165 mm reflectarray antenna operating in Ka-band (31.8-34.7 GHz) has been designed with and without the polarization conversion. The results prove that the polarization conversion can be achieved while maintaining the performance of the antenna.

En este trabajo se propone un análisis en términos de capacidad para una red de acceso centralizada compuesta por macro celdas y celdas pequeñas en interiores. Para ello, se emplean técnicas de coordinación de interferencia intercelda (ICIC- Inter-Cell Interference Coordination) y transmisión coordinada multi-punto (CoMP- Coordinated Multi-Point transmission/reception) evaluando su influencia en la red bajo distintos niveles de carga y políticas de coordinación. La fase de pruebas se lleva a cabo mediante el uso de una herramienta de planificación de redes radio. Con esta herramienta se evalúan las métricas de eficiencia espectral y asignación de recursos compartidos por celda, obtenidas sobre una red heterogénea Long-Term Evolution (LTE) real. Los resultados presentan las condiciones de carga y coordinación entre celdas necesarias para conseguir mejoras de capacidad en el sistema.

The fifth generation (5G) of mobile networks leads to novel services and heterogeneous scenarios that increase the complexity of management and orchestration tasks. In this context, Self-Organizing Networks (SON) are highly important to automatically monitor the network. This will allow to detect potential network failures and optimize the network performance. This paper proposes a methodology to automatically monitor a mobile network based on key performance indicators.

The Chair of the Spanish public broadcaster RTVE at the Universidad Politécnica de Madrid –UPM presented last October 2020 the first complete pilot broadcast, worldwide, of UHD 8K signal in DVB-T2. The broadcast included a signal characterized by a resolution of 7680x4320 pixels and new technologies such as High Dynamic Range with the HLG transfer function, High Frame Rate with 50 frames per second, Wider Colour Gamut following the ITU-R BT.2020 recommendation color space, 10-bit depth and 4:2:0 subsampling, and multichannel audio 5.1.4. The resulting bit rate of the audiovisual content was around 32 Mbps thanks to the use of very efficient standards, such as HEVC and Dolby AC-4, for the video and audio encoding, respectively. The DVB-T2 standard, with a COFDM modulation, was used for the transmission of the signal.

This paper analyses a simulation of performance in an intra-wagon environment based on four scenarios. The 28 GHz and the 37 GHz bands are assessed for the use of 5G millimeter (mmWave) communications. The main objective was to apply different multiple-input single-output orthogonal frequency division multiplexing (MISO-OFDM) techniques such as Hadamard quasi-orthogonal space-time block code (HQSTBC) and transmit beamforming to analyze the throughput achieved as a function of the signal-to-noise ratio (SNR) applied. Performance is analyzed by scenario, applied band and in terms of the two algorithms used. In addition, the results are simulated with 4 and 8 transmitting antennas.

El objetivo principal de este paper es presentar el piloto de Red.es en Castilla la Mancha en el que se realizará una transmisión y recepción de un canal de Televisión y Radio de TVE, con una red 5G Broadcast, en la ciudad de Toledo.

High-index dielectric disks with subwavelength dimensions seem relatively simple electromagnetic structures. However, they can give rise to exotic phenomena in nanophotonics. Here we show recent findings that show that high-index disks can be used to manipulate light in subwavelength dimensions as a result of Mie and Fabry-Perot resonances. We also propose that such disks can be used for new applications in photonic integrated circuits (PICs) using silicon technology.

The occurrence of many intriguing and useful non-classical phenomena lies in the interplay between interference and losses. Losses are usually understood as a detrimental effect, but they also constitute a degree of freedom for the engineering of quantum processes. Herein, we present a simplified procedure to compute the matrix describing quantum state transformations in N-ports lossy devices. This procedure could be applied to lossy devices with a scattering matrix that is unitarily diagonalizable. We employ the proposed method to analyze the performance that can be obtained when a Wilkinson power divider/combiner is excited with elementary quantum states of light. Our results suggest that Wilkinson power dividers/combiners could be of interest to optics and nanophotonics applications.

We exploit metamaterials being controlled in four dimensions (space and time) to manipulate and structure the propagation of electromangetic waves in real time. To do this, we make use of temporal boundaries where the permittivity of the medium in which the wave travels is changed rapidly in time from an isotropic to an anisotropic tensor. The physics behind such temporal boundaries will be described in detail showing how the direction of the energy propagation of the electromangetic wave can be tailored at will (temporal aiming). Moreover, it will be discussed how the amplitude of the backward wave generated by such temporal boundary can be completely eliminated (temporal Brewster angle).

En este trabajo, se presenta por primera vez un efecto de fading inducido por la dispersión con el objetivo de analizar estadísticamente su impacto en la intensidad óptica recibida de un sistema de comunicación óptica inalámbrica submarina (underwater optical wireless communication, UOWC) con el fin de proporcionar un modelo de canal UOWC más preciso que los existentes en la literatura actual. El modelo de fading desarrollado será utilizado para evaluar las prestaciones en términos de tasa de error de bit (bit error rate, BER) asintótica para altos valores de relación señal a ruido de un sistema UOWC bajo diferentes condiciones de dispersión. Los resultados obtenidos en este trabajo confirman el impacto del fading inducido por dispersión a través del empeoramiento de las prestaciones de la BER, así como una significativa penalización de potencia óptica en comparación con los sistemas donde se ignora la dispersión como fuente generadora de fading. Todos los resultados presentados aquí son validados mediante simulaciones Monte Carlo.

We present our study of the Mach-Zehnder modulator (MZM) and the transmission of pure tone radiofrequency signals through an optical fiber link. Our results show that the detected signal at the receiver vanishes at a specific frequency of the pure tone signal as a result of chromatic dispersion. The frequency notch in the link's transfer function experiences a shift as a consequence of the finite Extinction Ratio (ER) of the MZM. Here, we propose to compensate this effect using dual-drive modulators with a clever relationship between amplitudes of the signals in each electrode and analyze the range of values for which the approximation of small signal regime is valid.

Radar is an integral part of modern automotive ADAS/AD systems. This paper presents an overview of the technologies and topologies used in state-of-the art automotive radar, with special focus on the transceiver MMIC.

In this paper, a flat lens antenna using Gap Waveguide (GW) technology working in the millimeter waves band is designed. The metamaterial lens is fed using a Groove Gap Waveguide (GGW) horn antenna in order to achieve a plane wavefront at broadside. Both devices, metalens and GGW antenna achieve excellent radiation results when combined together. Due to the fully metallic composition, the structure presents more robustness, low loss, and adaptability to a flat surface, apt for millimeter wave application.

In this work, the design of a band-pass filter, based on a periodic structure that uses modified sections of a single-ridge waveguide (SRW) as the unit cell to produce the electromagnetic band-gap (EBG) at the desired frequency, is successfully addressed. The effect of the dimensions of the SRW height profiles in the different characteristics of the filter (lower cut-off frequency, and center frequency and bandwidth of the rejection-band) is analysed through the dispersion diagram of the infinitely periodic structure with different unit cells. The proposed topology and design process is used to implement a 54% fractional bandwidth band-pass filter centered at 5.4 GHz using low-cost 3D additive manufacturing techniques, which allow fast prototyping and the fabrication of complex geometries. Experimental measurements are in good agreement with the expected simulated response of the designed band-pass filter, showing good matching in the pass-band, and a deep rejection band.

In this article, three dual circularly-polarized K-band horn antennas are designed and experimentally validated. All designs are based on a common topology: a square waveguide input, a bowtie-shaped polarizer, and a flare section. Either left or right-handed radiation can be achieved by exciting one of the degenerate modes in the square waveguide. The bowtie polarizer outstands as a simple, easy-to-manufacture way of obtaining circular polarization. The three designs differ just in the flare section: a circular aperture, a square aperture and a bowtie-shaped aperture have been considered. The advantages of each aperture type will be discussed. The prototypes have been manufactured by Direct Metal Laser Sintering, allowing a single-block assembly. Over 20% bandwidth with axial ratio under 3 dB and gain around 19 dBi has been experimentally obtained in the three designs.

This paper presents the design, optimization and simulation of a novel 12x12 W-Band waveguide slotted array antenna based on stacked glide-symmetric metal sheets fed by a groove gap waveguide (GGW). This paper also proposes a new unit cell. The suggested unit cell has serpentine-shaped holes in a glide-symmetric configuration with the goal of minimizing the separation between parallel waveguides. To demonstrate the viability of the proposed unit cell, a 12x12 W-Band waveguide slotted array antenna at 92 GHz was designed and simulated. The results show that the proposed slot array antenna has a reflection coefficient below −10 dB within 91.3 GHz to 93 GHz, and the peak directivity and gain are about 29.7 dBi and 28.8 dB, respectively, at 92 GHz.

This paper shows in detail the 3D printing and electroplating process for a WR-28 rectangular waveguide. The characteristics of the printing process that must be taken into account to obtain the best possible print and to avoid problems that may arise are analyzed. Several studies are also carried out on the copper plating process using the electroplating method, changing the current applied to the piece, the amount of plating time and adding a copper deposition retardant additive that helps to reduce the roughness of the surfaces. In addition, possible errors that can lead to faulty electroplating are discussed.

Se presenta un sistema de antenas confocal para demostrar capacidades de escaneo de haz en banda W. El componente reconfigurable es un reflectarray basado en tecnología de cristal líquido (LC). Se realiza un análisis tipo full-wave para obtener la respuesta en frecuencia de las celdas del reflectarray, mientras que las Teorías Física de la Difracción (PTD) y de Física Óptica (PO) son utilizadas para calcular la reflexión de los campos electromagnéticos y los diagramas de radiación del sistema. Los resultados de la simulación ofrecen una ganancia máxima de 30 dB y un rango de escaneo de 20º en ambos planos: φ = 0º y φ=90º.

A comparison between the Ma-Rokhlin-Wandzura (MRW) and double exponential (DE) quadrature rules for the numerical integration of elements of the matrix of the moment method (MoM) with singular behavior in multilayer periodic structures is shown. Non Uniform Rational B-Splines (NURBS) modeling of layouts is implemented to provide a high-order description of geometry. The comparison is carried out to show which quadrature rule is more suitable for MoM matrix calculation in terms of sampling, accuracy and CPU time consumption. The results obtained in this comparison show that the CPU time consumption of numerical integration with MRW samples is approximately 15 times faster than numerical integration using DE samples. This promising result shows an efficient tool for the analysis of reflectarray elements with a high order of description of the geometry of the layout used, which is suitable for reflectarray designs under the assumption of local periodicity where a large number of elements have to be analyzed.

This contribution presents a reflectarray for X-band applications and a dedicated antenna measurement system to validate its performance. The reflectarray is designed to radiate two beams, one in X-polarization and one in Y-polarization. The reflectarray cell consists of a cross-shaped conductive element which, by varying one dimension, allows adjusting the focus of the beam generated in X-polarization and, by varying the other, the focus of the beam generated in Y-polarization. The antenna measurement system is a cost-effective 3D-printed roll-over-azimuth system to perform spherical acquisitions and has been designed for educational applications.

This paper describes the analysis and design of an

offset multi-faceted reflectarray structure composed of three

identical panels distributed following a parabolic cylinder.

Working in Ka-band, the antenna is designed to generate a

pencil beam in the broadside direction of the structure. Its

performance is compared with a flat reflectarray of similar

aperture size. The multi-faceted reflectarray design achieves a

significant improvement in band performance compared to its

classic single panel version.

This document presents the design and manufacture of a reflectarray (RA) antenna for the Ku-band, based on a fully-metallic 3D architecture. The reflectarray unit cell is formed by a square-shaped waveguide section ended in a short circuit, that is the reflectarray back ground plane. Each cell has the ability of configuring the phase of its own reflected field by means of resonators perforated on the walls of the cell waveguide section. The resonator-based waveguide cell introduces the 3D character to the design. The geometry of the resonators and its size variation introduces the phase behaviour of each cell, conforming the radiation pattern of the reflectarray. This design explores the potential of phase value truncation (6 states and 2 states), and demonstrates that proper pattern results can be obtained with this phase truncation.

Las ultimas décadas han sido testigo de espectaculares avances en la ingeniería sobre la interacción de la luz y la materia. El desarrollo de materiales nano estructurados ha permitido aumentar substancialmente la sensibilidad de diversos métodos de espectroscopia tales como la espectroscopia Raman o la espectroscopia infra-roja de absorción. Similarmente, en los últimos años se ha demostrado que ciertas nanopartículas dieléctricas y metálicas son también capaces de aumentar la interacción quiral de la luz y la materia. En particular, diversos trabajos han probado que estas nanopartículas (o antenas ópticas) permiten aumentar la sensibilidad de la espectroscopia de Dicroísmo Circular, así como la efectividad de métodos de separación de enantiómeros moleculares mediante fotólisis inducida por luz. Esta contribución repasa las capacidades de estas nano estructuras metálicas y dieléctricas para estas aplicaciones de identificación y resolución de moléculas quirales.

In recent years, optical designs have appeared as an alternative to traditional electronic-based computers in the search for a smaller footprint and energy consumption. However, the linearity of the wave equation has not been fully exploited as it allows for inherent parallelization due to bandwidth limitations of the optimized structures. In this work, we show that a metamaterial structure formed by an inverse-designed region enclosed in a transmissive cavity within a feedback-loop allows for the simultaneous solution of an arbitrary number of independent mathematical problems in a fully analog setup using waves at different frequencies. We demonstrate this capability both numerically and experimentally for two sets of discretized integral equations using a two-level multifrequency feedback system with tailor-made unidirectional exciting and probing antennas.

Drift-biased graphene has emerged as a promising platform for nonreciprocal plasmonics. Even though the properties of the supported surface plasmons have been theoretically explored by several groups, the far-reaching applications that drift-biased graphene may enable have not yet been fully explored. In this talk, we will first briefly review the response of drift-biased graphene metasurfaces considering nonlocal effects. Then, we will present and discuss a number of potential nanophotonic applications that are currently being explored in our group, including nano-optical tweezers, terahertz and infrared spasers, deeply subwavelength plasmonic imaging, and quasi-unidirectional hyperbolic plasmons. We will finalize by providing an outlook and critical assessment of this technology, in terms of advantages and limitations with respect to common graphene plasmonics as well as challenges that remain to be solved in realistic implementations.

In this work present a photonic integrated frequency signal generator based on an asymmetric mode-locked laser (MLL) structure with frequency repetition rate of 33 GHz. The device has been fabricated in monolithic Indium Phosphide (InP) platform. The structure is composed by two reflectors, two different size semiconductors optical amplifiers (SOA) sections and an asymmetrically located saturable absorber. The ML-PIC pulses are generated at the 33.86 GHz fundamental frequency exhibiting a 3dB-linewidth around 234 kHz with a drift less than 1 MHz measured over 20 minutes in passive operation regime and a phase-noise of around -55 dBc/Hz at 100 kHz

Passive radiative cooling refers to the ability to cool an object without any external energy input, exploiting the black body radiation phenomenon experienced by any material body at a given temperature. In order to maximize this cooling capacity, the body's emissivity function must be tuned to fulfill several specific properties. Some of them are already known in the literature, but no study has been carried out so far to find the optimum emissivity as a function of both the object temperature and the room temperature. In this paper it is analysed how these two variables affect the optimal emissivity function of an arbitray body so that its cooling power is maximized.