Harvest the ambient AM broadcast radio energy for wireless sensors

A wireless sensor system powered by AM broadcast energy harvesting is presented. A 10 meter length horizontal antenna and a resonant circuit were combined to harvest the electromagnetic energy, in the frequency range from 531 kHz to 1602 kHz. In a typical urban environment, an output voltage up to 14 V and a power of 82 mu W were obtained by a single stage doubler rectifier. A seven-day measurement is implemented to verify the stability of the energy. The output characteristics, multi stage doubler rectifier and implementation of sensor prototype are also discussed. The results indicate that the energy carried by AM radio is sufficient to drive a basic wireless sensor operating in sleep/wakeup mode. The stability and continuity of the harvested energy is superior to solar energy.