PhD defense Raziyeh Sharifi: Efficient Metasurface Energy Harvesters for IoT Applications
Télécom Paris, 19 place Marguerite Perey F-91120 Palaiseau [getting there], amphi 7 and in videoconferencing
Jury
- Nel SAMAMA, Professeur, Telecom SudParis (Jury president/ Examiner)
- Ala SHARAIHA, Professeur des Universités, Université de Rennes (Reviewer)
- Eric LHEURETTE, Professeur des Universités, Université de Lille (Reviewer)
- Ludivine FADEL, Maitre de Conférences – Université de Bordeaux (Examiner)
- Xavier BEGAUD, Professeur, Télécom Paris (Thesis director)
- Anne Claire LEPAGE, Maître de conférences, Télécom Paris (Thesis co-director)
- Kyriaki NIOTAKI, Maître de conférences, Télécom Paris (Guest/ Thesis co-supervisor)
Abstract
Wireless communications and the Internet of Things are becoming integral parts of modern life. By avoiding the need for batteries—thereby reducing the cost as well as the size and weight of appliances—energy harvesting by collecting ambient energy represents a promising alternative power supply. Ambient energy in the environment can be captured from various sources like solar, wind, or radio frequency signals, etc. While solar and wind energy are characterized by a high power density, these sources are not always available. Radio frequency signals, on the other hand, have the advantage of being ubiquitously present but have a comparatively low power density.
two common solutions are rectenna and metasurface for energy harvesting. To use absorbers in energy harvesting devices, the challenge is to maximize the collected energy and thus to minimize losses which occur in dielectrics. To do so, metasurfaces, with their low profile and absorption characteristics can be good candidates using a low-loss substrate.
In general, in energy harvesting devices based on metasurface, either multi-layer or planar structures can be used. The main drawback of multi-layer structures is the complexity of fabrication. Planar designs help to overcome this problem. Moreover, as the ambient radio frequency energy is usually low, it is necessary to collect most of it by improving the performance of the metasurface. To do so, in this thesis, compact efficient metasurface harvesters are proposed: a single-band design operating at 2.45 GHz and a dual-band design operating at 2.45 GHz, and 5.2 GHz.
Firstly, the metasurface structures have been designed. Given the low levels of ambient radio frequency energy, it is crucial to maximize the collected power. To address this challenge, an intermediate step in the design process is introduced to enhance the capturing efficiency of metasurface. This additional step is applied for both proposed single and dual-band designs. A finite array of 5×4 cells is presented for both designs. The simulated capturing efficiency of the central rows of the finite array for the single-band design is 90% at 2.54 GHz. The simulated capturing efficiency of the central rows of the finite array for the dual-band design is 74% at 2.5 GHz, and 30% at 5.09 GHz.
Secondly, a single-band rectifier circuit based on Schottky diodes is proposed to be integrated with the single-band metasurface structure, in order to convert the collected radio frequency energy to DC. The rectification efficiency at 2.49 GHz at the differential input of the rectifier at -2.7 dBm, is 58%.
Each proposed design of the metasurfaces and the rectifier has been analyzed independently. Then all have been fabricated and measured to verify their performance.