A compact RF energy harvesting system around 2.4 GHz

A compact radio frequency (RF) energy harvesting system around 2.4 GHz based on a Rogers 5880 substrate is proposed in this paper. Integrating a microstrip antenna, a rectifier and energy management circuits (EMC) on a single printed circuit board (PCB), the overall dimensions of the system can be miniaturized to 96.8 mm × 87.33 mm × 1.575 mm. The proposed antenna has a -29.45 dB reflection coefficient at the resonant frequency of 2.438 GHz, with an ideal 8.2 dBi gain simulated in the High-Frequency Structure Simulator. The rectification efficiency of the rectifier achieves as high as 37% when the input power is set at 5 dBm. Harvesting RF energy from an RF emitter, which consists of an RF signal source with 10 dBm output power and a power amplifier with 30 dB gain, the system could successfully power a hygrothermograph at a maximum distance of 15.14 m. In practical conditions, the system could drive the hygrothermograph when situated at a distance of 30 cm from a wireless router, where it could complete a charging cycle approximately every 30 seconds.