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

Abstract

Wireless self-powered systems based on RF energy harvesting (RFEH) have emerged as an effective solution to the energy challenges in Internet of Things (IoT) devices. 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 a 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% in the input power range of −8–15.5 dBm and exceeds 70% between 2.5 and 11.5 dBm. Even at −14 dBm, a power conversion efficiency (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 h at 1 m. This system provides a solution for the widespread application of IoT in the future.