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[EN] Massive multiple-input multiple-output (MIMO) is considered an enabling technology to achieve large capacities in multi-user scenarios in the upcoming mobile networks (5G and beyond). In this paper, the performance of the massive MIMO concept is investigated from measurement data at millimeter wave (mmWave) frequencies. The measurements were collected in an indoor office environment from 25 to 40 GHz in the frequency domain, using a virtual uniform rectangular array (URA) at the base station consisting of 144 (12×12) antennas. Line-of-Sight (LOS) and Obstructed-LOS (OLOS) propagation conditions have been considered. Both the favorable propagation condition and the achievable capacity are analysed in terms of active users and number of antennas placed at the base station. The results are particularised at the 26, 28 and 38 GHz bands adopted for the deployment of future wireless communication networks., Este trabajo ha sido financiado en parte por el Ministerio de Economía, Industria y Competitividad a través de los proyectos TEC2017-86779-C2-1-R y TEC2017-86779-C2-2-R, a través de la Agencia Estatal de Investigación (AEI) y el Fondo Europeo de Desarrollo Regional (FEDER).

[EN] Propagation channel models based on ray-tracing techniques can estimate, with some details, the specular multipath components reaching the receiver antenna, but have difficulty to estimate diffuse components. In this paper, an empirical model to include diffuse scattering in ray-tracing channel models, or channel simulators, is proposed. The diffuse scattering model has been developed from channel measurements collected from 25 to 40 GHz in the frequency domain, in both line-of-sight (LOS) and obstructed-LOS (OLOS) propagation conditions, in an office environment. The accuracy of a raytracing software to estimate time-dispersion metrics is evaluated when the diffuse scattering model is taken into account., Este trabajo ha sido financiado en parte por el Ministerio de Economía, Industria y Competitividad a través de los proyectos TEC2017-86779-C2-1-R y TEC2017-86779-C2-2- R, a través de la Agencia Estatal de Investigación (AEI) y el Fondo Europeo de Desarrollo Regional (FEDER).

[EN] In this contribution to the conference, we present different methods to improve the dynamic range of mobile radio channel measurements using a channel sounder in the frequency domain for millimeter wave (mmWave) propagation measurements. The advantages of using a radio over fiber (RoF) link are explained to avoid the losses introduced by a coaxial cable in measurements carried out in indoor and outdoor environments. Furthermore, measurements are carried out in a laboratory environment in order to obtain the optimal configuration parameters to carry out large measurement campaigns in the shortest possible time while maintaining the highest possible dynamic range and the correct calculation of the dispersion parameters. Finally, a simple protocol is disclosed to obtain the optimal parameters mentioned through three short steps., Este trabajo ha sido financiado en parte por el Ministerio de Economía, Industria y Competitividad a través del proyecto TEC2017-86779-C2-2-R (AEI/FEDER, UE).

Comunicación presentada en la XXXVI edición del Simposio Nacional de la URSI (Vigo, España), 20-24 septiembre 2021. 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. Este trabajo ha sido financiado por la Agencia Estatal de Investigación (AEI) con el proyecto PID2019-107688RB-C22.

[EN] In this contribution, we present a method for estimating the optimal size of moving average filter to ensure a precise separation of small and large scale fading effects. The analysis of small and large scale fading of the Vehicle-to-Vehicle (V2V) measured channel has been performed from narrowband channel measurements carried out in an urban environment at 5.9 GHz. Uniform intervals, where the channel process can be considered stationary, have been identified by comparing the cumulative distribution function (CDF) of the received envelope. A relationship between the length of the uniform intervals and the velocity of vehicles has been found. Moreover, the Rice K factor has been estimated for each one of these intervals. Our results showed that the proposed method is adequate to carry out a small and large scale fading separation. The results obtained make its use interesting to process correctly measured data in vehicular environments., Este trabajo ha sido financiado por el Ministerio de Economía, Industria y Competitividad de España a través del proyecto TEC2017-86779-C2-2-R.

[ES] Se presenta una guia de onda ranurada con polarizacion dual circular y alimentada por una guia de onda Groove Gap (GGW) y que funciona en la banda Ka. Se propone un mecanismo simple para cambiar la polarizacion circular a ¿ derechas por circular a izquierdas, y viceversa. La tapa de la antena tiene dos piezas: una fija y otra deslizante. La pieza fija alberga ranuras en forma de T, y el bloque deslizante se encarga de ajustar el desplazamiento de las ranuras perpendiculares con respecto a las ranuras longitudinales. Los resultados preliminares muestran una relacion axial por debajo de 1.5 dB para ambos ¿ sentidos de polarizacion circular, dentro de un ancho de banda ¿ de 1 GHz centrado en 30 GHz., Este trabajo ha sido apoyado por el Ministerio de Ciencia, Innovación y Universidades en el marco del proyecto TEC2016-79700-C2-1-R.

[EN] In this conference contribution, we present millimeter-wave (mmWave) propagation measurements for an office environment from 25 to 40 GHz and investigate the path loss using the most common empirical models proposed in WINNER-II and adopted by the 3GPP: the single-frequency floating-intercept (FI) model, the single-frequency close-in (CI) free space reference distance model, the multi-frequency alphabeta-gamma (ABG) model and the close-in free space reference distance with frequency path loss exponent (CIF). Both line-ofsight (LOS) and obstructed-LOS (OLOS) propagation conditions have been considered. The mean value of the model parameters, and their 95 % confidence intervals, have been derived using regression and optimization techniques., Este trabajo ha sido financiado en parte por el Ministerio de Economia, Industria y Competitividad a traves de los proyectos TEC2016-78028-C3-2-P, TEC2017-86779-C2-1-R y TEC2017-86779-C2-2-R, a traves de la Agencia Estatal de Investigacion (AEI) y el Fondo Europeo de Desarrollo Regional (FEDER) y por COLCIENCIAS en Colombia.

Comunicación presentada en URSI'19, XXXIV Simposium Nacional de la Unión Científica Internacional de Radio, Sevilla, 4-6 septiembre 2019. This paper reports the design and measurements of two radiating panels (TX / RX) for satellite communications on the move in Ka-band. A multilayer structure, both in the power distribution network and in the circularly-polarized radiating element, is adopted to ensure the demanded bandwidth. These panels provide answers and solve problems for future antennas with similar characteristics. Las actividades que han llevado a la obtención de estos resultados han sido financiadas parcialmente por la Agencia Espacial Europea bajo el contrato 400010860913NLUS- proyecto LOCOMO y por el Ministerio de Economía y Competitividad bajo el proyecto TEC2013-47360-C3-3-P.

[EN] This letter focuses on comparing manufacturing features of three-dimensional (3-D) printing techniques versus conventional computer numerical control (CNC) milling in the context of gap waveguide technology. To this end, a single-layer array antenna has been designed as a demonstrator. The antenna under test, intended for Ka-band, is composed of 8 x 8 radiators fed by a gap-waveguide (GW) corporate network. Two identical prototypes have been manufactured, but each applying a different fabrication technique, i.e., 3-D printing and CNC milling. The experimental results of both antennas are presented, under the same conditions and measurement facilities. The conclusions drawn in this letter provide a valuable assessment of 3-D-printing viability for GW arrays against the conventional milling technique., This work was supported by the Spanish Ministry of Economy and Competitiveness (Ministerio de Economia y Competitividad) under Grant TEC2016-79700-C2-1-R.

[EN] This paper summarizes the research that has been developed by the authors for the last six years, concerning the design of planar wideband antennas for portable devices. Basic structures combining electric and magnetic elements are proposed, which lead to antennas with large bandwidth. Thus, by using these basic structures, a polarization diversity antenna, a wideband antenna for DVB-H applications and a wideband MIMO antenna have been proposed for wireless applications in mobile terminals. Prototypes of all the antennas have been fabricated and measured at iTEAM and/or CWC facilities., This work was supported by the Spanish Ministerio de Economía y Competitividad under the projects TEC2010-20841-C04-01 and CSD2008-00068, and by the Finnish Funding Agency for Technology and Innovation (Tekes projects AATE and MIMOTA) and its industrial partners, EB, ETS Lindgren, Nokia Devices Oulu and Pulse Finland Inc. Mr. Sonkki also would like to thank the Nokia Foundation and the Infotech Oulu Doctoral Program for financially supporting his PhD studies.

[EN] Vehicular-to-Vehicular (V2V) communications are receiving considerable attention due to the introduction of the intelligent transportation system (ITS) concept. To design, evaluate and optimize ITS applications oriented to vehicular safety based on wireless systems, the knowledge of the propagation channel is vital, in particular the path loss. From a narrowband V2V channel measurements campaign carried out in a suburban area of the city of Valencia (Spain), this paper analyzes the path loss in terms of the transmitter (Tx) and receiver (Rx) separation distance. Based on a linear slope model, values for the path loss exponent and the standard deviation of shadowing are reported. Also, the Doppler Power Spectral Density (PSD) due to the time-selective behavior is examined., This work has been funded in part by the Programa de Apoyo a la Investigación y Desarrollo de la Universitat Politècnica de València (PAID-05-10) and the Departamento Administrativo de Ciencia, Tecnología e Innovación COLCIENCIAS de Colombia.

A compact printed multimode antenna for Multiple-Input Multiple-Output (MIMO) systems is presented. The antenna consists of a slotted metallic ring antenna excited by four L-shaped microstrip feeding lines, which are necessary to generate four orthogonal radiating modes. The proposed antenna exhibits a performance similar to traditional antenna arrays in MIMO systems, and due to its compact size it is very suitable for mobile terminals or sensors. The Theory of Characteristic Modes is first used to identify the different radiating modes of the antenna and then a set of feeding configurations is proposed so as to excite these modes. A compact printed 2-stage network of 180° hybrid couplers is implemented to feed the proposed antenna. Measured S-parameters and radiation patterns confirm the excellent behavior of the proposed antenna.