PHD Defense Inès KHARRAT

The work presented in this thesis is part of microwave energy harvesting theme, applied to supply electrochromic displays for anti-counterfeiting applications. This study focuses on the design, optimization and implementation of rectennas (rectifying antennas) printed on cellulosic substrates with industrial printing techniques.
Characterization of dielectric materials (paper) and conductors has been developed. The combination between the transmission line technique and the resonant cavity allowed the characterization of a flexible and copper free substrate over a wideband (500 MHz to 3 GHz). Dielectric losses of paper are too high to perform HF circuits. A wise choice of the substrate and of the optimization technique for circuit design enables performant rectennas.
Two compact rectennas were developed in microstrip technology at 2.45 GHz, optimized and printed with flexography method using a single layer of conductive ink. The rectennas do not contain vias or HF side filter or DC side filter. The first rectenna was printed on corrugated paper. The output DC voltage across the display reaches 0.5 V for a power level at the input of the rectenna of -10 dBm. The second rectenna is a 3D rectenna, printed on flexible 100 µm thick plastic substrate. A DC voltage of 1 V was measured across the display when getting near a Smartphone on Wi-Fi mode. The rectennas are suitable for both near field and far field.

Keywords : characterization, paper substrate, rectenna, Schottky diode, electrochromic display

Members of  jury :
Pascal XAVIER - Supervisor
Tan-phu VUONG - Co supervisor
Philippe BENECH - Examiner
Laurent CIRIO - Rapporteur
Jean-Daniel LAN SUN LUK - Rapporteur
Anthony GHIOTTO - Examiner