Analysis and Design of Reconfigurable Antennas Using the Theory of Characteristic Modes

[ES] La Teoría de los Modos Característicos, formulada originalmente en 1968, permite obtener un conjunto de valores propios reales y modos de corriente reales que se pueden utilizar para expandir la corriente total en un cuerpo conductor o dieléctrico. La información proporcionada por las corrientes características (modos) y los valores propios se puede utilizar para realizar el diseño de la antena de una manera sistemática. La gran ventaja de la Teoría de los Modos Característicos sobre otros métodos de diseño tradicionales es la clara visión física que se proporciona sobre los fenómenos que contribuyen a la radiación de la antena. Esta visión física permite comprender mejor el funcionamiento de la antena, de modo que el diseño y la optimización de la misma se pueden llevar a cabo de forma rápida y coherente. El objetivo de esta Tesis es extender el uso de la Teoría de los Modos Característicos al diseño de antenas reconfigurables de manera sistemática. El uso de antenas reconfigurables se ha vuelto cada vez más importante en los últimos años, como una forma de cumplir con los requisitos impuestos y el rendimiento deseado en los nuevos sistemas de comunicaciones inalámbricas. El enfoque de hacer una antena reconfigurable implica la capacidad de una antena para ajustar sus características, como la frecuencia de operación, el diagrama de radiación y la polarización. Diversos componentes activos como diodos varactor, diodos PIN, MEMS, interruptores de RF, elementos fotoconductores o materiales inteligentes pueden usarse para cambiar estas características básicas de la antena. La reconfiguración dinámica de los parámetros operativos de una antena conduce a un sistema de comunicación flexible. Las antenas reconfigurables por frecuencia permiten el mantenimiento de múltiples estándares mientras se mantienen las mismas características físicas de las antenas. La antena reconfigurable por radiación y la diversidad de polarización permiten aumentar la eficiencia de las comunicaciones interiores al reducir significativamente el nivel de interferencia. En esta tesis, la investigación gira en torno al análisis y diseño de estructuras de antenas con la Teoría de los Modos Característicos de manera que los parámetros de las antenas sean sintonizables, por lo que el diseño final de la estructura es una antena reconfigurable que modifica dinámicamente su rendimiento de una forma razonada y coherente. Se analizarán los modos característicos y sus propiedades para diseñar antenas reconfigurables, que combinarán diferentes modos y producirán diferentes características de radiación. En este trabajo se implementará un método sistemático para obtener las características requeridas de la antena. Además, se analizarán y evaluarán diferentes técnicas de conmutación para evaluar su efecto real en la antena y en los modos característicos. El trabajo se centrará en el diseño de pequeñas antenas reconfigurables para aplicaciones IoT y sistemas 5G.[CA] La Teoria dels Modes Característics, formulada originalment el 1968, permet obtenir un conjunt de valors propis reals i modes de corrent reals que es poden utilitzar per expandir el corrent total en un cos conductor o dielèctric. La informació proporcionada pels corrents característics (modes) i els valors propis es pot utilitzar per fer el disseny de l'antena d'una manera sistemàtica. El gran avantatge de la Teoria dels Modes Característiques sobre altres mètodes de disseny tradicionals és la clara visió física que es proporciona sobre els fenòmens que contribueixen a la radiació de l'antena. Aquesta visió física permet comprendre millor el funcionament de l'antena, de manera que el disseny i l'optimització de la mateixa es poden dur a terme de forma ràpida i coherent. L'objectiu d'aquesta Tesi és estendre l'ús de la Teoria dels Modes Característics al disseny d'antenes reconfigurables de manera sistemàtica. L'ús d'antenes reconfigurables s'ha tornat cada cop més important en els darrers anys, com una forma de complir amb els requisits imposats i el rendiment desitjat en els nous sistemes.temes de comunicacions sense fil. L'enfocament de fer una antenna reconfigurable implica la capacitat duna antena per ajustar les seves característiques, com la frequ¿ència d'operació, el diagrama de radiació i la polarització. Diversos components actius com va donar dos varactor, díodes PIN, MEMS, interruptors de RF, elements fotoconductors o materials intel·ligents poden utilitzar-se per canviar aquestes característiques bàsiques de l'antena. La reconfiguració dinàmica dels paràmetres operatius duna antena condueix a un sistema de comunicació flexible. Les antenes reconfigurables per frequ¿ència permeten el manteniment de múltiples estàndards mentre es mantenen les mateixes característiques físiques de les antenes. L'antena reconfigurable per radiació i diversitat de polarització permeten augmentar l'eficiència de les comunicacions interiors en reduir significativament el nivell dinterferència. En aquesta tesi, la investigació gira al voltant de l'anàlisi i el disseny de estructures d'antenes amb la Teoria dels Modes Característics de manera que els paràmetres de les antenes siguin sintonitzables, per això que el disseny final de lestructura és una antena reconfigurable que modifica dinàmicament el seu rendiment d'una forma raonada i coherent. S'analitzaran els modes característics i les propietats per dissenyar antenes reconfigurables, que combinaran diferents maneres i produiran diferents característiques de radiació. En aquest tractament baix s'implementarà un mètode sistemàtic per obtenir les característiques requerides de l'antena. A més, s'analitzaran i avaluaran diferents tècniques de commutació per avaluar el seu efecte real a la antena i en les maneres característiques. El treball se centrarà en el disseny de petites antenes reconfigurables per a aplicacions IoT i sistemes 5G.[EN] The Theory of Characteristic Modes, originally formulated in 1968, allows to obtain a set of real eigenvalues and real current modes that can be used to expand the total current on a conducting or dielectric body. The information provided by characteristic eigencurrents (modes) and eigenvalues can be used to perform antenna design in a systematic way. The great advantage of the Theory of Characteristic Modes over other traditional design methods is the clear physical vision provided about the phenomena that contribute to the radiation of the antenna. This physical vision allows to better understand the operation of the antenna, so that the design and the optimization of it can be carried out quickly and coherently. The objective of this Thesis is to extend the use of the Theory of Characteristic Modes to the design of reconfigurable antennas in a systematic way. The use of reconfigurable antennas has become more and more important during the last years, as a way to meet the imposed requirements and desired performance of novel wireless communication systems. The approach of making an antenna reconfigurable implies the capability of an antenna system to adjust its characteristic such as operating frequency, radiation pattern and polarization. Active components such as varactor diodes, PIN diodes, MEMS, RF switches, photoconductive elements or smart materials can be used to change these base characteristics. The dynamic reconfigurability of the operating parameters of an antenna leads to a flexible communication system. Frequency reconfigurable antennas enable multi-standard performances to be maintained while preserving the same physical characteristics of the antennas. Radiation reconfigurable and polarisation diversity antennas enable to increase the efficiency of indoor communications by significantly decreasing the level of interference. In this thesis, the research is turning around the analysis and design of antenna structures with the Theory of Characteristic Modes in a way that the antenna parameters will be tuneable, so the final design of the structure is a reconfigurable antenna that modifies dynamically its performance in a reasoned and coherent way. Characteristic modes and their properties will be analysed in order to design reconfigurable antennas, which combine different modes and produce different radiation characteristics. A systematic method to obtain the required characteristics of the antenna will be implemented during this work. Moreover, different switching techniques will be analysed and evaluated in order to asses their real effect on the antenna and on the characteristic modes. In this work, small reconfigurable antenna prototypes will be designed for IoT applications and 5G systems.This study was supported by the Spanish Ministry of Science and Innovation (Ministerio Ciencia e Innovación) under project no. PID2019-107885GB-C32 and Generalitat Valenciana under project no. AICO/2019/018. This work has also been supported by the Spanish Ministry of Science, Innovation and Universities (Ministerio Ciencia, Innovación y Universidades) under the project TEC2016- 78028-C3-3-P and by “Centre National pour la Recherche Scientifique et Technique (CNRST, Maroc)” as part of the research excellence scholarships programMahlaoui Boudallaa, Z. (2023). Analysis and Design of Reconfigurable Antennas Using the Theory of Characteristic Modes [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/20155

Radiation Pattern Reconfigurable Antenna for IoT Devices

[EN] Based on the characteristic mode theory, a versatile radiation pattern reconfigurable antenna is proposed. )e analysis starts from two parallel metallic plates with the same and different dimensions. By means of two PIN diodes, the size of one of the parallel metallic plates can be modified and consequently the behavior of the radiation pattern can be switched between bidirectional and unidirectional radiation patterns. Moreover, a SPDT switch is used to adjust the frequency and match the input impedance. )e reconfigurable antenna prototype has been assembled and tested, and a good agreement between simulated and measured results is obtained at 2.5 GHz band which fits the IoT applications.This study was supported by the Spanish Ministry of Science and Innovation (Ministerio Ciencia e Innovacion) under project no. PID2019-107885GB-C32 and Generalitat Valenciana under project no. AICO/2019/018.Mahlaoui, Z.; Antonino Daviu, E.; Ferrando Bataller, M. (2021). Radiation Pattern Reconfigurable Antenna for IoT Devices. International Journal of Antennas and Propagation (Online). 2021:1-13. https://doi.org/10.1155/2021/5534063S113202

Radiation Pattern Agile Antenna using PIN Diodes and SPDT Switches

[EN] In this paper, a new design of a reconfigurable antenna is proposed. The antenna structure is using two PIN diodes for switching between two radiation patterns (directional and bidirectional) and a SPDT switch to achieve good impedance matching. The simulated results show a good impedance matching, with S11 below -10 dB using the SPDT switch configuration. In addition, the far-field directivity for both configurations is around 5 dB.Zakaria, M.; Antonino Daviu, E.; Ferrando Bataller, M. (2020). Radiation Pattern Agile Antenna using PIN Diodes and SPDT Switches. IEEE. 1771-1772. https://doi.org/10.1109/IEEECONF35879.2020.9329761S1771177

Design of a Dual-Band Frequency Reconfigurable Patch Antenna Based on Characteristic Modes

[EN] A frequency reconfigurable patch antenna design based on the characteristic mode analysis is presented. The antenna presents a reconfigurable lower band and a steady band at higher frequencies. A slot is etched on the ground plane of the antenna, where two varactor diodes are placed on each side of the slot in order to tune the lower band. The first resonant frequency shifts down by varying the reverse voltage of the varactor, whereas the second operating frequency keeps stable. The proposed antenna is designed to cover WLAN bands, offering a first band operating at 2GHz and a second band ranging from 5.3GHz to 5.8GHz. A prototype has been fabricated and measurements are provided, which validate the proposed analysis, method, and design procedure.This work has been supported by the Spanish Ministry of Science, Innovation and Universities (Ministerio Ciencia, Innovacion y Universidades) under the project TEC2016-78028-C3-3-P.Mahlaoui, Z.; Antonino Daviu, E.; Latif, A.; Ferrando Bataller, M. (2019). Design of a Dual-Band Frequency Reconfigurable Patch Antenna Based on Characteristic Modes. International Journal of Antennas and Propagation (Online). 2019:1-12. https://doi.org/10.1155/2019/4512532S1122019Zhu, F., Gao, S., Ho, A. T., Abd-Alhameed, R. A., See, C. H., Brown, T. W. C., … Xu, J. (2013). Multiple Band-Notched UWB Antenna With Band-Rejected Elements Integrated in the Feed Line. IEEE Transactions on Antennas and Propagation, 61(8), 3952-3960. doi:10.1109/tap.2013.2260119Cui, Y. H., Zhang, P. P., & Li, R. L. (2018). Broadband quad‐polarisation reconfigurable antenna. Electronics Letters, 54(21), 1199-1200. doi:10.1049/el.2018.5244Qin, P.-Y., Guo, Y. J., & Ding, C. (2013). A Dual-Band Polarization Reconfigurable Antenna for WLAN Systems. IEEE Transactions on Antennas and Propagation, 61(11), 5706-5713. doi:10.1109/tap.2013.2279219Elfergani, I. T. E., Hussaini, A. S., See, C. H., Abd-Alhameed, R. A., McEwan, N. J., Zhu, S., … Clarke, R. W. (2014). Printed monopole antenna with tunable band-notched characteristic for use in mobile and ultra-wide band applications. International Journal of RF and Microwave Computer-Aided Engineering, 25(5), 403-412. doi:10.1002/mmce.20874Nguyen-Trong, N., Hall, L., & Fumeaux, C. (2016). A Frequency- and Pattern-Reconfigurable Center-Shorted Microstrip Antenna. IEEE Antennas and Wireless Propagation Letters, 15, 1955-1958. doi:10.1109/lawp.2016.2544943Wright, M. D., Baron, W., Miller, J., Tuss, J., Zeppettella, D., & Ali, M. (2018). MEMS Reconfigurable Broadband Patch Antenna for Conformal Applications. IEEE Transactions on Antennas and Propagation, 66(6), 2770-2778. doi:10.1109/tap.2018.2819818Liu, Q., Wang, N., Wu, C., Wei, G., & Smolders, A. B. (2015). Frequency Reconfigurable Antenna Controlled by Multi-Reed Switches. IEEE Antennas and Wireless Propagation Letters, 14, 927-930. doi:10.1109/lawp.2014.2386694Simorangkir, R. B. V. B., Yang, Y., Hashmi, R. M., Bjorninen, T., Esselle, K. P., & Ukkonen, L. (2018). Polydimethylsiloxane-Embedded Conductive Fabric: Characterization and Application for Realization of Robust Passive and Active Flexible Wearable Antennas. IEEE Access, 6, 48102-48112. doi:10.1109/access.2018.2867696Antonino-Daviu, E., Cabedo-Fabres, M., Sonkki, M., Mohamed Mohamed-Hicho, N., & Ferrando-Bataller, M. (2016). Design Guidelines for the Excitation of Characteristic Modes in Slotted Planar Structures. IEEE Transactions on Antennas and Propagation, 64(12), 5020-5029. doi:10.1109/tap.2016.2618478Harrington, R., & Mautz, J. (1971). Theory of characteristic modes for conducting bodies. IEEE Transactions on Antennas and Propagation, 19(5), 622-628. doi:10.1109/tap.1971.113999

Rilpivirine in HIV-1-positive women initiating pregnancy: to switch or not to switch?

International audienceBackgroundSafety data about rilpivirine use during pregnancy remain scarce, and rilpivirine plasma concentrations are reduced during second/third trimesters, with a potential risk of viral breakthroughs. Thus, French guidelines recommend switching to rilpivirine-free combinations (RFCs) during pregnancy.ObjectivesTo describe the characteristics of women initiating pregnancy while on rilpivirine and to compare the outcomes for virologically suppressed subjects continuing rilpivirine until delivery versus switching to an RFC.MethodsIn the ANRS-EPF French Perinatal cohort, we included women on rilpivirine at conception in 2010–18. Pregnancy outcomes were compared between patients continuing versus interrupting rilpivirine. In women with documented viral suppression (<50 copies/mL) before 14 weeks of gestation (WG) while on rilpivirine, we compared the probability of viral rebound (≥50 copies/mL) during pregnancy between subjects continuing rilpivirine versus those switching to RFC.ResultsAmong 247 women included, 88.7% had viral suppression at the beginning of pregnancy. Overall, 184 women (74.5%) switched to an RFC (mostly PI/ritonavir-based regimens) at a median gestational age of 8.0 WG. Plasma HIV-1 RNA nearest delivery was <50 copies/mL in 95.6% of women. Among 69 women with documented viral suppression before 14 WG, the risk of viral rebound was higher when switching to RFCs than when continuing rilpivirine (20.0% versus 0.0%, P = 0.046). Delivery outcomes were similar between groups (overall birth defects, 3.8/100 live births; pregnancy losses, 2.0%; preterm deliveries, 10.6%). No HIV transmission occurred.ConclusionsIn virologically suppressed women initiating pregnancy, continuing rilpivirine was associated with better virological outcome than changing regimen. We did not observe a higher risk of adverse pregnancy outcomes