This PhD work focuses on the design and optimization of RF energy harvesting systems for autonomous IoT nodes. The objective is to develop efficient rectifier and antenna architectures capable of operating at very low input power levels, paving the way for battery-less connected devices. Key questions addressed include: what rectifier topology provides the best trade-off between efficiency and sensitivity, how can flexible biocompatible antennas maintain performance under body influence, and to what extent can integrated RF-powered systems compete with industrial RFID solutions?
The methodology relies on three main steps: (i) design and characterization of multi-stage Schottky rectifiers with resistance compression networks (RCN) for improved robustness, (ii) development of dual-band PDMS-based antennas, including AMC integration for enhanced gain and reduced detuning, and (iii) implementation of a proof-of-concept RFID system combining a rectifier and a tunnel diode oscillator. By correlating simulations with fabricated prototypes and experimental measurements, the proposed approach demonstrates a 1 V supply at short range and an ultra-low-power RFID tag with a record activation sensitivity of –28.1 dBm and 90 m range.
The final outcome contributes to advancing RF energy harvesting technology, enabling sustainable, compact, and autonomous IoT sensors.
