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167 178 75 ; S ; [EN] This paper reports on the development of a compact, low-cost, impulse bi-static UWB radar sensor for its use as non-destructive methods for electrical property measurement in industrial application. This UWB Radar sensor consists of an ultrashort-monocycle-pulse transmitter of 330 ps, an oscilloscope as a UWB sampling receiver with a high wide band of 6 GHz, and two UWB antennas ranging from 0.4 to 6 GHz. A new model of SRD has been introduced to decrease the rise time of the impulse. Performance of this UWB radar sensor was verified through two kinds of applications: range detection and electrical property measurements. All measurements have been carried out in an anechoic chamber with a distance variation between 80 and 300 cm. The full radar system provides good agreement between the experimental and theoretical results, which demonstrate its application in many fields, especially for electrical Property Measurements. The authors gratefully acknowledge the financial support provided by Pierre and Marie Curie University under the EMMAG Scholarship. This study was supported by DIMAS group, ITACA institute at City polytechnic of innovation from university polytechnic of Valencia. Ahajjam, Y.; Aghzout, O.; Catalá Civera, JM.; Penaranda-Foix, FL.; Driouach, A. (2018). An Advanced Electrical Properties Measurement Approach with a Designed Bi-Static Ultra-Wideband Impulse Radar Sensor. Progress in Electromagnetics Research-PIER. 75:167-178. https://doi.org/10.2528/PIERM18070305

[EN] This paper describes the use of microwave technology to identify anti-counterfeiting markers on banknotes. The proposed method is based on a robust near-field scanning microwave microscope specially developed to measure permittivity maps of heterogeneous paper specimens at the micrometer scale. The equipment has a built-in vector network analyzer to measure the reflection response of a near-field coaxial probe, which makes it a standalone and portable device. A new approach employing the information of a displacement laser and the cavity perturbation technique was used to determine the relationship between the dielectric properties of the specimens and the resonance response of the probe, avoiding the use of distance-following techniques. The accuracy of the dielectric measurements was evaluated through a comparative study with other well-established cavity methods, revealing uncertainties lower than 5%, very similar to the accuracy reported by other more sophisticated setups. The device was employed to determine the dielectric map of a watermark on a 20 EUR banknote. In addition, the penetration capabilities of microwave energy allowed for the detection of the watermark when concealed behind dielectric or metallic layers. This work demonstrates the benefits of this microwave technique as a novel method for identifying anti-counterfeiting features, which opens new perspectives with which to develop optically opaque markers only traceable through this microwave technique. ; This paper has been financially supported through the grant reference BES-2016-077296 of the call Convocatoria de las ayudas para contratos predoctorales para la formacion de doctores de 2016 by Ministerio de Economia y Competitividad (MINECO) and by European Social Funds (ESF) of European Union, and the project SEDMICRON-TEC2015-70272-R (MINECO/FEDER) supported by Ministerio de Economia y Competitividad (MINECO) and by European Regional Development Funds (ERDF) of European Union. ; Gutiérrez Cano, JD.; Catalá Civera, JM.; Plaza González, ...

© 2018 IEEE. Personal use of this material is permitted. Permissíon from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertisíng or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. ; [EN] A novel dielectrometer to measure the complex permittivity of high-loss liquids is presented. The geometry consists of a reentrant cavity with insertion holes, where the holder filled with liquid can be introduced readily. Radii of the insertion holes are large enough for a convenient pouring of the liquid. The electromagnetic analysis has been performed by a mixed mode-matching and circuit technique with the purpose of taking the high accuracy and fast convergence of the mode-matching and the flexibility and versatility of the circuit method. The convergence of the method is studied, and a procedure to estimate the result for an infinite number of modes is proposed. A calibration procedure is presented to minimize the error introduced by the numerical method. Mode charts are shown to analyze the behavior of resonant parameters for every mode. Some reference liquids are measured at different resonant frequencies, and the results are compared with those provided by other models of the literature. ; This work was supported in part by the "Programa de Ayudas de Investigacion y Desarrollo de la Universitat Politecnica de Valencia," in part by the Ministerio de Economia y Competitividad-Spanish Government under Project TEC2012-37532-C02-01, and in part by the European Regional Development Funds of European Union. ; Marqués-Villarroya, D.; Canós Marín, AJ.; Penaranda-Foix, FL.; García-Baños, B.; Catalá Civera, JM. (2018). Full-Wave Modal Analysis of a Novel Dielectrometer for Accurate Measurement of Complex Permittivity of High-Loss Liquids at Microwave Frequencies. IEEE Transactions on Microwave Theory and Techniques. ...

[EN] An enhanced full-wave method based on circuit analysis is presented in this paper, where the whole set of modes TEmnp and TMmnp are taken into account. The modeling of a split cylinder resonator is done with two circuit networks of one and three ports, characterized by their generalized admittance matrix, which is computed making use of the mode matching method. The improved full-wave circuit method has been applied to the accurate determination of dielectric properties of materials. The proposed method has been validated through comparisons with other published models and also with measurements. ; This work was supported in part by the Ministerio de Economia y Competitividad-Spanish Government and in part by the European Regional Development Funds of European Union under Project SEDMICRON - TEC2015-70272-R (MINECO/FEDER). The work of D. Marqucs-Villarroya was supported by the Universitat Politccnica de Valencia through the Programa para la formacion de personal investigador de la UPV. The work of F.L. Penarada-Foix was supported by the Conselleria de Educacion of the Generalitat Valenciana (BEST/2016/012). ; Marqués-Villarroya, D.; Penaranda-Foix, FL.; García-Baños, B.; Catalá Civera, JM.; Gutiérrez Cano, JD. (2017). Enhanced Full-Wave Circuit Analysis for Modeling of a Split Cylinder Resonator. IEEE Transactions on Microwave Theory and Techniques. 65(4):1191-1202. https://doi.org/10.1109/TMTT.2016.2637932 ; S ; 1191 ; 1202 ; 65 ; 4

1191 1202 65 4 ; S ; [EN] An enhanced full-wave method based on circuit analysis is presented in this paper, where the whole set of modes TEmnp and TMmnp are taken into account. The modeling of a split cylinder resonator is done with two circuit networks of one and three ports, characterized by their generalized admittance matrix, which is computed making use of the mode matching method. The improved full-wave circuit method has been applied to the accurate determination of dielectric properties of materials. The proposed method has been validated through comparisons with other published models and also with measurements. This work was supported in part by the Ministerio de Economia y Competitividad-Spanish Government and in part by the European Regional Development Funds of European Union under Project SEDMICRON - TEC2015-70272-R (MINECO/FEDER). The work of D. Marqucs-Villarroya was supported by the Universitat Politccnica de Valencia through the Programa para la formacion de personal investigador de la UPV. The work of F.L. Penarada-Foix was supported by the Conselleria de Educacion of the Generalitat Valenciana (BEST/2016/012). Marqués-Villarroya, D.; Penaranda-Foix, FL.; García-Baños, B.; Catalá Civera, JM.; Gutiérrez Cano, JD. (2017). Enhanced Full-Wave Circuit Analysis for Modeling of a Split Cylinder Resonator. IEEE Transactions on Microwave Theory and Techniques. 65(4):1191-1202. https://doi.org/10.1109/TMTT.2016.2637932

[EN] In this work, the carbothermic reduction of iron- and zinc-bearing products is studied through in situ microwave heating, dielectric properties monitoring, and mass spectrometry up to high temperatures (1000 degrees C). The results are correlated to the information provided by conventional analysis techniques such as differential scanning calorimetry (DSC) and thermogravimetry (TG). This combination allows a detailed study of seven different process stages with an accurate determination of the reaction temperatures, providing new evidence about the particular conditions of this microwave-driven reduction process. The presented results suggest that molecular vibrations imposed by the microwave field are presumably the reason for reactions taking place at lower temperatures than those observed in the conventional process. This work also explores the influence of other parameters, such as the apparent density or the amount of carbonaceous material, on the resulting dielectric properties, providing useful information for the development of a potential microwave industrial application in the metallurgy field. ; This research was funded by the European Union's Horizon 2020 research and innovation programme under Grant Agreement number 820783. ; García-Baños, B.; Catalá Civera, JM.; Sánchez-Marín, JR.; Navarrete Algaba, L.; López-Buendía, AM.; Schmidt, L. (2020). High Temperature Dielectric Properties of Iron- and Zinc-Bearing Products during Carbothermic Reduction by Microwave Heating. Metals. 10(5):1-15. https://doi.org/10.3390/met10050693 ; S ; 1 ; 15 ; 10 ; 5 ; Omran, M., Fabritius, T., & Mattila, R. (2015). Thermally assisted liberation of high phosphorus oolitic iron ore: A comparison between microwave and conventional furnaces. Powder Technology, 269, 7-14. doi:10.1016/j.powtec.2014.08.073 ; Omran, M., Fabritius, T., Heikkinen, E.-P., & Chen, G. (2017). Dielectric properties and carbothermic reduction of zinc oxide and zinc ferrite by microwave heating. Royal Society Open Science, 4(9), 170710. ...

Lithium aluminosilicate was fabricated by conventional and non-conventional sintering: microwave and spark plasma sintering, from 1200 to 1300 ºC. A considerable difference in densification, microstructure, coefficient of thermal expansion behavior and hardness and Young's modulus was observed. Microwave technology made possible to obtain fully dense glass-free lithium aluminosilicate bulk material (>99%) with near-zero and controlled coefficient of thermal expansion and relatively high mechanical properties (7.1 GPa of hardness and 110 GPa of Young's modulus) compared to the other two processes. It is believed that the heating mode and effective particle packing by microwave sintering are responsible to improve these properties. ; The authors would like to thank Dr. Emilio Rayon for performing the nanoindentation analysis in the Materials Technology institute (ITM) of the Polytechnic University of Valencia (UPV) and your financial support received of UPV under project SP20120621 and SP20120677 and Spanish government through the project (TEC2012-37532-C02-01) and cofunded by ERDF (European Regional Development Funds). A. Borrell acknowledges the Spanish Ministry of Science and Innovation for a Juan de la Cierva contract (JCI-2011-10498) and SCSIE of the University of Valencia. ; Benavente Martínez, R.; Salvador Moya, MD.; Borrell Tomás, MA.; García Moreno, O.; Peñaranda Foix, FL.; Catalá Civera, JM. (2015). Microwave, spark plasma and conventional sintering to obtain controlled thermal expansion beta-eucryptite materials. International Journal of Applied Ceramic Technology. 1-7. https://doi.org/10.1111/ijac.12285 ; S ; 1 ; 7 ; Bach, H. (Ed.). (1995). Low Thermal Expansion Glass Ceramics. Schott Series on Glass and Glass Ceramics. doi:10.1007/978-3-662-03083-7 ; Roy, R., Agrawal, D. K., & McKinstry, H. A. (1989). Very Low Thermal Expansion Coefficient Materials. Annual Review of Materials Science, 19(1), 59-81. doi:10.1146/annurev.ms.19.080189.000423 ; García-Moreno, O., Kriven, W. M., Moya, J. S., & ...

Microwave heating is proposed as non-conventional technique for the sintering of optimal lithium aluminosilicate compositions of β-eucryptite system. The coefficient of thermal expansion and mechanical properties of the sintered samples has been studied under the influence of microwave heating. The ad hoc synthesized β-eucryptite together with the microwave sintering technique developed in this work open the opportunity to produce breakthrough materials with low or negative coefficient of thermal expansion and excellent mechanical properties, as a Young s modulus of 110 GPa. The combination of rapid heating with low energy applied by the microwave technology (eco-friendly process) and the dramatic reduction in cycle time allows densification without glass phase formation. Results of the coefficient of thermal expansion of the β-eucryptite ceramics presented here under cryogenic conditions will be of value, for example, in the future design of new composite materials for space applications ; The authors would like to thank Dr. Emilio Rayon for performing the nanoindentation analysis in the Materials Technology institute (ITM) of the Polytechnic University of Valencia (UPV) and your financial support received of UPV under Projects SP20120621 and SP20120677 and Spanish Government through the Project MONIDIEL (TEC2008-04109). A. Borrell, acknowledges the Spanish Ministry of Science and Innovation for a Juan de la Cierva contract (JCI-2011-10498) and SCSIE of the University of Valencia. ; Benavente Martínez, R.; Borrell Tomás, MA.; Salvador Moya, MD.; Garcia-Moreno, O.; Penaranda-Foix, FL.; Catalá Civera, JM. (2014). Fabrication of near-zero thermal expansion of fully dense beta-eucryptite ceramics by microwave sintering. Ceramics International. 40(1):935-941. https://doi.org/10.1016/j.ceramint.2013.06.089 ; S ; 935 ; 941 ; 40 ; 1

"© 2020 IEEE. Personal use of this material is permitted. Permissíon from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertisíng or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works." ; [EN] This paper reports the development of a stand-alone and portable instrument designed to measure the complex permittivity of dielectric materials at microwave frequencies. The equipment consists of an in-house single-port vectorial reflectometer and a resonant coaxial bi-reentrant microwave cavity where the material under test is placed inside a Pyrex vial, making the device appropriate for measuring liquids, semi-solids, powders and granular materials. The relation between the dielectric properties of the involved materials and the cavity resonance has been solved by numerical methods based on mode-matching and circuit analysis. In order to increase the measurement range, so that low to high loss materials can be characterized in the same cavity, the effect of the coupling network is de-embedded from the resonance measurements. The performance of the newly devised instrument is evaluated by error/uncertainty analysis and comparative studies with other well-established instruments and methods. Errors lower than 2% in the dielectric constant, and 5% in the loss factor, are found. This simple, portable, affordable and robust device could help non-specialized personnel to accurately measure dielectric properties of materials used in a wide range of microwave applications. ; This paper has been financially supported through the grant reference BES-2016-077296 of the call Convocatoria de las ayudas para contratos predoctorales para la formacion de doctores de 2016 by Ministerio de Economia y Competitividad (MINECO) and by European Social Funds (ESF) of European Union and the project SEDMICRON TEC2015-70272-R (MINECO/FEDER) supported ...

[EN] Hydrogen is a promising vector in the decarbonization of energy systems, but more efficient and scalable synthesis is required to enable its widespread deployment. Towards that aim, Serra et al. present a microwave-based approach that allows contactless water electrolysis that can be integrated with hydrocarbon production. Supplying global energy demand with CO2-free technologies is becoming feasible thanks to the rising affordability of renewable resources. Hydrogen is a promising vector in the decarbonization of energy systems, but more efficient and scalable synthesis is required to enable its widespread deployment. Here we report contactless H-2 production via water electrolysis mediated by the microwave-triggered redox activation of solid-state ionic materials at low temperatures ( 250 degrees C). Water was reduced via reaction with non-equilibrium gadolinium-doped CeO2 that was previously in situ electrochemically deoxygenated by the sole application of microwaves. The microwave-driven reduction was identified by an instantaneous electrical conductivity rise and O-2 release. This process was cyclable, whereas H-2 yield and energy efficiency were material- and power-dependent. Deoxygenation of low-energy molecules (H2O or CO2) led to the formation of energy carriers and enabled CH4 production when integrated with a Sabatier reactor. This method could be extended to other reactions such as intensified hydrocarbons synthesis or oxidation. ; This work was supported by the Spanish Government (RTI2018-102161, SEV-2016-0683 and Juan de la Cierva grant IJCI-2017-34110). We thank the support of the Electronic Microscopy Service of the Universitat Politecnica de Valencia. ; Serra Alfaro, JM.; Borras-Morell, JF.; García-Baños, B.; Balaguer Ramirez, M.; Plaza González, PJ.; Santos-Blasco, J.; Catalán-Martínez, D. (2020). Hydrogen production via microwave-induced water splitting at low temperature. Nature Energy. 5(11):910-919. https://doi.org/10.1038/s41560-020-00720-6 ; S ; 910 ; 919 ; 5 ; 11 ; Serra, J. M. ...