26-229 MULTI-PORT, COMPACT DIELECTRIC ANTENNA EXPLOITING MULTI-MODAL PROPERTIES

26-229 MULTI-PORT, COMPACT DIELECTRIC ANTENNA EXPLOITING MULTI-MODAL PROPERTIES* Ph.D., 36 months* Full-time * Experience : no preference* Master degree* TelecommunicationsContextThe aim of this work is to exploit the modal diversity of a dielectric resonator antenna (DRA) to propose a single-band multi-port antenna. When the excited modes operate at the same frequency, it is possible to reconfigure the radiation pattern and polarization, paving the way for advanced applications such as multiple-input multiple-output (MIMO) systems, localization, and scanned-null pattern. Additionally, when using orthogonal modes, the antenna is also called a vector antenna (VA).The specific properties of VA can be exploited in different applications as for instance : • Direction finding that can be used for distress signal search, autonomous navigation, and radio spectrum monitoring. For the first two applications, the direction finder must be onboard. In this case, the sensor must be small to minimize its size and weight. A VA is then an attractive solution for minimizing the complexity of integration. • Global navigation satellite systems (GNSS) that can be vulnerable to intentional or accidental interference. Controlled radiation pattern antennas (CRPA) capable of beamforming and null-steering are therefore a particularly interesting technological solution. Thus, this approach can improve the robustness and reliability of critical systems such as those used in aeronautics, defense, and civil infrastructure. • MIMO antennas that are used in 4G / 5G networks, satellite communication systems, and Internet of things (IoT) networks to optimize the use of the radio spectrum. To minimize signal correlation, spatial and polarization diversity can be employed.The common requirements for these applications are reduced coupling between elements and compactness. While the collocation of orthogonal radiating modes theoretically insures good radiation properties with polarization diversity, it remains difficult to feed each mode independently without degrading the isolation between them. Furthermore, to achieve multimodal radiation at a single-band frequency, it may be necessary to use materials engineering to translate the appropriate resonances into a single operating frequency.At ENAC, several research projects have focused on developing vector sensors for detecting emergency beacons in the GSM band [1,2] and for aircraft positioning in the 5G band [3]. These studies have demonstrated the capabilities of VAs for estimating the direction of arrival (DoA) of electromagnetic waves in 3D space using small antenna sensors [4]. In collaboration with ISAE-SUPAERO, the control of the modal frequency of a DRA has been thoroughly studied in previous works [5,6,7] and has demonstrated the ability to exploit the inhomogeneity, anisotropy, and dispersion of 3D-printed artificial dielectric materials.Objective In this PhD work, we propose to manufacture an antenna capable of having six orthogonal radiation patterns at the same frequency band.It turns out that the resonating modes of a parallelepiped DRA are well understood. For a cubic shape, three orthogonal magnetic dipole-like modes exist along each axis of a Cartesian coordinate system as fundamental modes at the same frequency. Three additional orthogonal electric modes exist at a higher frequency. These electric and magnetic modes are orthogonal to each other due to their polarization characteristics.The first challenge is to reduce the frequency of these electric modes to that of the three fundamental ones. To achieve this, we plan to exploit the anisotropic and inhomogeneous properties of 3D-printed artificial dielectric materials.The second challenge is driving these modes independently in order to preserve their orthogonality properties while minimizing coupling between ports and avoiding excitation of spurious modes at nearby resonating frequencies. To minimize the impact of these spurious modes, an additional degree of freedom is necessary. With this in mind, the frequency shift behaviors of the proper and improper modes can be separated by considering anisotropic and inhomogeneous materials. Another approach is to cancel the excitation of some improper modes using a specific feeding circuit that exploits symmetry and antisymmetry properties.In the end, this PhD work should enable the development of a compact and multi-port DRA suitable for a wide variety of applications.[1] J. Lominé et al., in IEEE Trans. Antennas Propag., vol. 63, no. 8, Aug. 2015,[2] J. Duplouy, et al., in IEEE Trans. Antennas Propag., vol. 67, no. 6, June 2019.[3] H. Obaid, et al., in IEEE Sensors Letters, vol. 7, no. 10, Oct. 2023.[4] C. Morlaas, et al., in IEEE URSI-APS , Montreal, QC, Canada, 2020.[5] C.D. Morales, et al., in Electron. Lett., 57, 2021.[6] B.J. De Araùjo, et al., in IET Microw. Antennas Propag. 18(4), 2024.[7] C.D. Morales, et al., in IET Microw. Antennas Propag., 19, 2025.=================For more Information about the topics and the co-financial partner (found by the lab!); contact Directeur de thèse christophe.morlaas@recherche.enac.fr Then, prepare a resume, a recent transcript and a reference letter from your M2 supervisor / engineering school director and you will be ready to apply online before March 13th, 2026 Midnight Paris time!### Location Location Address7 Avenue Edouard Belin, 31400 Toulouse, France

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