Nuestros investigadores

Juan Ignacio Sancho Seuma

Publicaciones científicas más recientes (desde 2010)

Autores: Sancho Seuma, Juan Ignacio (Autor de correspondencia); Pérez Hernández, Noemí; de Nó Lengaran, Joaquín; et al.
Revista: SENSORS
ISSN 1424-8220  Vol. 19  Nº 23  2019 
Inductor-capacitor (LC) passive wireless sensors are widely used for remote sensing. These devices are limited in applications where multiparameter sensing is required, because of the mutual coupling between neighboring sensors. This article presents two effective decoupling techniques for multiparameter sensing, based on partially overlapped sensors and decoupling coils, which, when combined, reduce the mutual coupling between sensors to near zero. A multiparameter LC sensor prototype with these two decoupling mechanisms has been designed, simulated, and measured. This prototype is capable of simultaneously measuring four parameters. The measurements demonstrate that the changes in capacitance in one individual sensor do not affect the measurements of the other sensors. This principle has been applied to simultaneous wear sensing using four identical wear sensors.
Autores: Ortego Isasa, Iñaki; Benli, K.P.; Casado, F.; et al.
ISSN 0278-0046  Vol. 64  Nº 10  2017  págs. 7749 - 7757
The potential of inkjet printing technology (IjP) for the fabrication of coils for biomedical applications in inductively coupled power transfer systems is studied in terms of needed compensations, bifurcation phenomena, and power transfer efficiency. The effect of using coils manufactured with IjP in the secondary side has been analyzed by studying the effect of the increase in internal resistance. The present study makes it possible to select the best topology depending on the load impedance, the coupling coefficient, and coil design. In terms of the compensations needed at the primary side, IjP does not significantly affect the behavior of the system; however, the series¿series topology is preferable since the compensating capacitance is independent from the internal resistance. In terms of bifurcation, a more restricted condition is obtained for parallel compensated secondary circuits. There is a decrease on the power transfer efficiency due to the increase of the internal resistance introduced by IjP. However, it is important to select the best topology according to the application since the decrease could be from 63% to only 6%. It is concluded that IjP is a promising fabrication technique for coils for biomedical applications.
Autores: Casado, F.; Arriola, A.; Arruti, E.; et al.
ISSN 0013-5194  Vol. 51  Nº 7  2015  págs. 546 - 547
A simple method is presented for estimating the resonant frequency of compact slotted microstrip antennas, based on their current distribution. The method has been first tested in two basic and symmetric geometries; afterwards, through the combination of these geometries, a multi-slotted structure has been analysed. Prototypes have also been manufactured in RT/Duroid 6002 and FR4 substrates, and good agreement has been obtained between estimations, simulations and measurements. A maximum estimation error of 10% has been achieved with this method, providing a useful tool for the design of compact slotted microstrip antennas.
Autores: Casado, F.; Arriola, A.; Arruti, E.; et al.
ISSN 0895-2477  Vol. 56  Nº 11  2014  págs. 2676 - 2681
This work presents a study of the impact of PIN diodes on the performance of reconfigurable compact microstrip antennas with high frequency-ratio. To this purpose, two frequency reconfigurable microstrip antennas with a frequency-ratio of 3 (868 MHz and 2.45 GHz ISM bands) and a different degree of compactness have been designed and measured for various PIN-diode configurations. The results show the derivative effects of using PIN diodes in the conditions mentioned, namely current cancelation, power dissipation, and frequency shift, and how to reduce their impact. The most significant repercussion is in the radiation efficiency, which can be enhanced from 46 to 74% using a less compact design, and by reducing the forward resistance of the PIN diode, what increases the radiation efficiency by a factor of 4. (C) 2014 Wiley Periodicals, Inc.
Autores: Ortego Isasa, Iñaki; Sanchez, N.; Garcia, J.; et al.
ISSN 1687-5869  2012 
The aim of this paper is to examine the potential of inkjet printing technology for the fabrication of Near Field Communication (NFC) coil antennas. As inkjet printing technology enables deposition of a different number of layers, an accurate adjustment of the printed conductive tracks thickness is possible. As a consequence, input resistance and Q factor can be finely tuned as long as skin depth is not surpassed while keeping the same inductance levels. This allows the removal of the typical damping resistance present in current NFC inductors. A general methodology including design, simulation, fabrication, and measurement is presented for rectangular, planar-spiral inductors working at 13.56 MHz. Analytical formulas, computed numerical models, and measured results for antenna input impedance are compared. Reflection coefficient is designated as a figure of merit to analyze the correlation among them, which is found to be below -10 dB. The obtained results demonstrate the suitability of this technology in the fabrication of low cost, environmentally friendly NFC coils on flexible substrates.
Autores: Garcia, J.; Arriola, A.; Casado, F.; et al.
ISSN 1751-8725  Vol. 6  Nº 9  2012  págs. 1070 - 1078
This study presents a comparison between two dipoles acting as representatives of ultra-high frequency radio frequency identification (RFID) circularly polarised (CP) and linearly polarised (LP) tag antennas, respectively. As the CP dipole is derived from the LP dipole, they have equivalent reflection coefficient and radiation efficiency values, allowing the comparison to be focused on polarisation and radiation pattern. Then, a comparison of RFID angular and read range is investigated. This is conducted by combining the interrogation of CP and LP tags emulators by CP and LP readers with regulated power. The emulators are made up of the CP and LP dipoles embedded onto RFID tags with analog front-ends. A methodology is described for measuring the maximum angular and read ranges, involving maximum power allowed by European regulation. A 17.9% extra range is achieved by the CP tag and the CP reader compared to the LP tag with any kind of reader. Furthermore, null cancellation is observed in the former case in the region of interest.
Autores: Gutierrez, S.; Sancho Seuma, Juan Ignacio; Fontán Agorreta, Luis; et al.
ISSN 1070-9878  Vol. 19  Nº 5  2012  págs. 1774 - 1781
This paper presents an analysis to determine the effect of the stress enhancement factor due to the presence of protrusions in the semiconductor shields of HVDC cables. The theoretical analysis of the electric field containing protrusions is based on a harmonic solution for the electric field for spherical and spheroidal protrusions. HVDC analysis takes into account the additional space charge accumulation due to the presence of protrusions.
Autores: Arriola, A.; Sancho Seuma, Juan Ignacio; Brebels, S.; et al.
ISSN 1751-8725  Vol. 5  Nº 7  2011  págs. 852 - 859
A stretchable antenna is proposed for body area networks operating at 2.45 GHz. The topology of the antenna is based on a meandered dipole with a parasitic arm, which has an impedance with a dual-resonance behaviour. The antenna impedance is optimised for the specific radio-frequency integrated circuit where it will be connected to. This topology has been implemented on two stretchable technologies using thermoplastic poly-urethane and silicone as substrates. A simple stretching model has also been proposed for design purposes and it has been validated through measurements. Simulations based on this model and real stretching measurements have shown the potential of the structure for obtaining a wideband match in stretched conditions, with optimised designs achieving a reflection coefficient lower than 210 dB up to 20% stretching. On-body simulations and measurements have also been done, which indicate that practical values of reflection coefficient and radiation efficiency can be achieved with a separation of few millimetres between the antenna and the human body.
Autores: Sancho Seuma, Juan Ignacio; Mendizábal Samper, Jaizki; Gurutzeaga Zubillaga, Iñaki; et al.
ISSN 0895-2477  Vol. 53  Nº 12  2011  págs. 2742 - 2746
Transmitting antenna in a Railway Spot Signalling System needs to be optimized in order to ensure data transfer reliability and minimize the required power. This paper analyses the improvement of the HF transmitting antenna taking into account the size of the receiving antenna, the presence of metallic objects and the misalignment between transmitting and receiving antennas. A novel HF transmitting antenna structure is proposed and verified to improve the read range. (C) 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53: 2742-2746, 2011; View this article online at DOI 10.1002/mop.26400
Autores: Valderas Gázquez, Daniel; Sancho Seuma, Juan Ignacio; Puente, D.; et al.
Ultrawideband (UWB) technology, positioned as the cutting edge of research and development, paves the way to meet the emerging demands set by broadband wireless applications, such as high-speed data transmission, medical imaging, short-range radars, electromagnetic testing, etc. This breathtaking resource builds upon the basics of UWB technology to provide a complete compilation of figures of merit along with a vital state-of-the-art of the different antenna alternatives that are to be employed according to the specific application. Without excessive recourse to mathematics, this volume emphasizes on the UWB antenna design and equips readers with practical prediction techniques based on simple formulas and models. The big picture of UWB antenna technology would not be complete without addressing its applications, and this will serve to provide consultants with key clues for market gap analysis. Containing over 150 supporting illustrations and figures, this comprehensive overview of UWB technology, antenna design and applications is a vital source of information and reference for R&D organizations, researchers, practitioners, consultants, RF professionals and communication engineers.