Wireless sensor node remote supply using a compact stacked rectenna array with voltage multipliers at 2.45 GHz

This paper presents compact rectenna arrays for ambient RF energy harvesting on the 2.45 GHz ISM band. The arrays are based on four and nine series-connected rectenna cells. Each cell is composed of a stacked fractal antenna and an RF-to-dc conversion circuit. The antenna is a compact third Koch fractal shape, fed by a coaxial probe for more compactness. The conversion circuit is a full-wave rectifier with a differential output, each DC polarity is provided by a two-stage Dickson voltage multiplier. Measurement results show a significant increase of the output DC voltage for the one, four, and nine cells rectenna arrays. They provide, for power density of 1.7 μW/cm 2 , an output DC voltage of 0.9, 2.2, and 4.1 Volts, respectively. The 9 cells rectenna array is used in a remote supply experiment of a temperature and acceleration wireless sensor, where the data are transmitted via a Bluetooth low energy link to a distant smartphone every 1 min.