Full-wave analysis of dielectric-loaded cylindrical waveguides and cavities using a new four-port ring network

“© 2012 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising 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.”In this paper, a full-wave method for the electromagnetic analysis of dielectric-loaded cylindrical and coaxial waveguides and cavities is developed. For this purpose, a new four-port ring network is proposed, and the mode-matching method is applied to calculate the generalized admittance matrix of this new structure. A number of analyses on dielectric-loaded waveguide structures and cavities have been conducted in order to validate and to assess the accuracy of the new approach. The results have been compared with theoretical values, numerical modeling from the literature, and data from commercial electromagnetic simulators. The method has been also applied to the accurate determination of dielectric properties, and we provide an example of these measurements as another way to validate this new method. © 1963-2012 IEEE.This work was supported by the Ministry of Science and Innovation of Spain under Project MONIDIEL (TEC2008-04109). The work of F. L. Penarada-Foix was supported by the Conselleria de Educacion of the Generalitat Valenciana for economic support (BEST/2010/210).Penaranda-Foix, FL.; Janezic, MD.; Catalá Civera, JM.; Canós Marín, AJ. (2012). Full-wave analysis of dielectric-loaded cylindrical waveguides and cavities using a new four-port ring network. IEEE Transactions on Microwave Theory and Techniques. 60(9):2730-2740. https://doi.org/10.1109/TMTT.2012.2206048S2730274060

Full-Wave Modal Analysis of a Novel Dielectrometer for Accurate Measurement of Complex Permittivity of High-Loss Liquids at Microwave Frequencies

© 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. 66(12):5760-5770. https://doi.org/10.1109/TMTT.2018.2881136S57605770661

A New Stand-Alone Microwave Instrument for Measuring the Complex Permittivity of Materials at Microwave Frequencies

"© 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 by Ministerio de Economia y Competitividad (MINECO) and by European Regional Development Funds (ERDF) of European Union. The Associate Editor coordinating the review process was Samir Trabelsi.Gutiérrez Cano, JD.; Plaza González, PJ.; Canós Marín, AJ.; García-Baños, B.; Catalá Civera, JM.; Penaranda-Foix, FL. (2020). A New Stand-Alone Microwave Instrument for Measuring the Complex Permittivity of Materials at Microwave Frequencies. IEEE Transactions on Instrumentation and Measurement. 69(6):3595-3605. https://doi.org/10.1109/TIM.2019.2941038S3595360569

Dynamic Measurement of Dielectric Properties of Materials at High Temperature During Microwave Heating in a Dual Mode Cylindrical Cavity

A microwave cavity and heating system for microwave processing and in situ dynamic measurements of the complex permittivity of dielectric materials at high temperatures (~1000ºC) has been developed. The method is based on a dual-mode cylindrical cavity where heating and testing are performed by two different swept frequency microwave sources. A cross-coupling filter isolates the signals coming from both sources. By adjusting the frequency bandwidth of the heating source and the level of coupling to the cavity, an automatic procedure allows for the establishment of a desirable level of heating rate to the dielectric sample to reach high temperatures in short cycles. Dielectric properties of materials as a function of temperature are calculated by an improved cavity perturbation method during heating. Accuracy of complex permittivity results has been evaluated and an error lower than 5% with respect to a rigorous analysis of the cavity has been achieved. The functionality of the microwave dielectric measurement system has been demonstrated by heating and measuring glass and ceramic samples up to 1000ºC. The correlation of the complex permittivity with the heating rate, temperature, absorbed power, and other processing parameters can help to better understand the interactions that take place during microwave heating of materials at high temperatures compared to conventional heating.Manuscript received February 17, 2015; revised May 08, 2015 and June 22, 2015; accepted June 27, 2015. Date of publication July 20, 2015; date of current version September 01, 2015. This work was supported by the Ministerio de Economia y Competitividad (MINECO) under Project TEC2012-37532-C02-01 and by the European Regional Development Funds (ERDF).Catalá Civera, JM.; Canós Marín, AJ.; Plaza González, PJ.; Gutiérrez Cano, JD.; García Baños, B.; Penaranda-Foix, FL. (2015). Dynamic Measurement of Dielectric Properties of Materials at High Temperature During Microwave Heating in a Dual Mode Cylindrical Cavity. IEEE Transactions on Microwave Theory and Techniques. 63(9):2905-2914. https://doi.org/10.1109/TMTT.2015.2453263S2905291463

Noninvasive monitoring of polymer curing reactions by dielectrometry

A microwave sensor system for the noninvasive monitoring of the curing process of a thermoset material placed inside a metallic mold is described. The microwave sensor is designed as an open-ended coaxial resonator with a curved surface adapted to the mold inner shape. The analysis of the microwave resonator comprises a recently developed method for deembedding the effect of coupling network in overcoupled resonators, so the range of permitted measurements encompass both low and high dielectric losses of polymeric materials. Results show that noninvasive, continuous monitoring of the microwave dielectric properties of the thermoset material can be performed in real time, allowing one to check initial conditions and to verify the evolution of the cure process. © 2006 IEEE.Manuscript received January 11, 2010; revised May 07, 2010; accepted May 09, 2010. Date of publication June 10, 2010; date of current version October 29, 2010. The work of B. Garcia-Banos was supported by a contract from the Ministry of Science and Innovation of Spain, through the "Torres Quevedo" Sub-programme, which is also cofinanced by the European Social Fund (ESF). This work was supported in part by the Comunitat Valenciana Government (IMPIVA - FEDER). The associate editor coordinating the review of this manuscript and approving it for publication was Prof. Evgeny Katz.García Baños, B.; Canós Marín, AJ.; Peñaranda Foix, FL.; Catalá Civera, JM. (2011). Noninvasive monitoring of polymer curing reactions by dielectrometry. IEEE Sensors Journal. 11(1):62-70. doi:10.1109/JSEN.2010.2050475S627011

A Novel Technique for Deembeding the Unloaded Resonance Frequency from Measurements of Microwave Cavities

[EN] A novel technique to extract the influence of coupling networks on the resonant frequency of cavities in one-port measurements is presented. The determination of the unloaded resonant frequency is performed directly from measurements without either the need to obtain the electromagnetic fields in the resonator or to deembed the delay of transmission lines from the measuring equipment to the resonator. The importance of the Foster's form on the modeling of the frequency detuning of the resonators is also discussed and a criterion for the choice of the appropriate Foster's form is suggested. The procedure is validated with simulations and experimental measurements of manufactured cavitiesCanós Marín, AJ.; Catalá Civera, JM.; Penaranda-Foix, FL.; Reyes Davó, EDL. (2006). A Novel Technique for Deembeding the Unloaded Resonance Frequency from Measurements of Microwave Cavities. IEEE Transactions on Microwave Theory and Techniques. 54(8):3407-3416. https://doi.org/10.1109/TMTT.2006.8778333407341654

Improvement in the Accuracy of Dielectric Measurement of Open-Ended Coaxial Resonators by an Enhanced De-Embedding of the Coupling Network

An improvement of the accuracy of dielectric measurements of the open-ended coaxial resonator method is described. The technique is based on an empirical technique for de-embedding the coupling network excited by electric probes. By this procedure, the influence of the coupling structure on the resonance can be precisely eliminated independently of the coupling conditions, which guarantees a high accuracy in the permittivity determination of materials by open-ended coaxial resonators. The technique is applicable to materials with a wide range of dielectric constants and losses. The results of dielectric measurements are compared with those obtained using other standard methods.The work of F. L. Penaranda-Foix was supported by the Conselleria d'Educacio of the Generalitat Valenciana for Economic Support (BEST/2012/010). This paper is an expanded paper from the IEEE MTT-S International Microwave Symposium, Seattle, WA, USA, June 2-7, 2013.Canós Marín, AJ.; García Baños, B.; Catalá Civera, JM.; Penaranda-Foix, FL.; Gutiérrez Cano, JD. (2013). Improvement in the Accuracy of Dielectric Measurement of Open-Ended Coaxial Resonators by an Enhanced De-Embedding of the Coupling Network. IEEE Transactions on Microwave Theory and Techniques. 61(12):4636-4645. https://doi.org/10.1109/TMTT.2013.2285359S46364645611