Articles techniques et présentations

This work reports the application of topology optimization for the design of two types of metallic antennas that are very different from each other: a leaky-wave antenna (LWA) radiating at broadside, and an epidermal patch antenna, optimized to favor radiation coupling into the human body. Planar leaky-wave antennas are traveling-wave antennas in which the wave “leaks” energy into space while propagating along the structure [“Substrate Integrated Waveguide Leaky Wave Antenna”, Application ID: 16021]. A leaky wave has a complex wavenumber and radiates away from the surface at an angle which depends on the phase constant; it can be generated from a surface wave by modulating the surface impedance of the antenna [A. A. Oliner and D. R. Jackson, “Leaky-wave antennas” in Antenna Engineering Handbook, McGraw-Hill (2007)]. LWAs notoriously suffer from the open stopband (OSB) at broadside, a phenomenon typical of periodic structures that causes a dramatic drop in the realized gain, thus effectively preventing radiation in this direction. A way to create LWAs radiating at broadside consists in using metasurfaces. Starting from the method described in [M. Zucchi, F. Vernì, M. Righero, and G. Vecchi, “Current Based Automated Design of Realizable Metasurface Antennas With Arbitrary Pattern Constraints,” IEEE Trans. Antennas Propag., vol. 71, no. 6, pp. 4888-4902 (2023)] it is indeed possible to achieve linearly-polarized broadside radiation using a single-layer isotropic metasurface [L. Teodorani et al., “Full-Wave Validation of Broadside Radiating MTS Antennas Designed with a Current-Based Approach”, COMSOL Conference 2023, Munich]. In this work, we will present a 2D preliminary example prepared by the COMSOL Support team showing the possibility to use the topological optimizer implemented in COMSOL Multiphysics to optimize the metallic antenna part of a flat planar antenna [E. Hassan et al. “Topology Optimization of Metallic Antennas”, IEEE Trans. Antennas Propag., vol. 62, no. 5, pp. 2488-2500 (2014)]; the goal of the optimization is to find the metal distribution which allows the antenna to efficiently radiate at broadside. The other reported example concerns the 3D topological optimization of the metal surface of an on-body antenna embedded into a dielectric block, designed to transmit and receive signals using the Fat-Intrabody Communication (Fat-IBC) technique, which exploits the low electrical conductivity of the fat tissue (0.11 S/m) to propagate signals through the subcutaneous fat layer [N. B. Asan, C. Pérez Penichet, S. Redzwan Mohd Shah, D. Noreland, E. Hassan, A. Rydberg, T. J. Blokhuis, T. Voigt, and R. Augustine, “Data packet transmission through fat tissue for wireless intrabody networks,”IEEE J. Electromagn., RF, Microw. Med. Biol., vol. 1, no. 2, pp. 43–51 (2017)].