A High-Efficiency Self-Powered Wireless Sensor Network Driven by Ambient RF Energy Far-Field

Wireless self-powered systems based on RF energy harvesting (RFEH) have emerged as an effective solution to the energy challenges in the Internet of Things devices (IoT). However, two critical challenges still persist: low energy harvesting efficiency at the receiver under low power conditions typical of long-distance scenarios, and the power range of RFEH not being suitable for most low-power IoT applications. To solve these problems, we proposed a high-efficiency RFEH system with wide input power range and high sensitivity. We employed harmonic suppression technology to mitigate higher-order harmonics generated by diodes and used radial stubs instead of capacitors and inductors to reduce insertion losses and parasitic effects. The proposed rectifier achieves a peak power efficiency of 74.4 % at 9.5 dBm. Efficiency remains above 50 % within the input power range of -8 to 15.5 dBm and exceeds 70 % between 2.5 to 11.5 dBm. Even at -14 dBm, a PCE of 30 % is maintained, significantly improving the efficiency of RFEH. Building on this RFEH system, we propose a dual-mode self-powered wireless sensor network system. Experimental results demonstrate that the low-power mode can operate up to 6 m away and have a minimum sensitivity of -10 dBm. The high-power (7 mW) mode can continuously monitor strain information for over 4.5 hours at 1 m. This system provides a solution for the widespread application of IoT in the future.