An alternative energy source for low power autonomous sensors

This paper details the feasibility of a microwave energy harvesting system capable of generating DC power from the ambient electromagnetic field as the one from a GSM base-station, and in a sufficient amount to replace batteries in specific low-power applications. The basic principle of such a system is detailed. A low power RF/DC rectifier has been designed and fabricated as well as a 4-element patch antenna array. The receiver was submitted to energy densities similar to those encountered in the vicinity of GSM base-stations and output DC voltages in excess of 400 mV have been measured.