Harvesting and conversion of the environmental electromagnetic pollution into electrical energy by novel rectenna array coupled with resonant micro-converter

Abstract

This paper introduces a novel device composed by a wide band rectifying antenna array coupled with a modified resonant amortized Armstrong oscillator with increased efficiency, used as step-up micro-converter. The aim of the device is to harvest ambient electromagnetic energy and convert it into useful energy. Experimental methods and simulations were used to design the microstrip rectenna and the micro-converter prototypes. One rectenna array composed by 48 microstrip antennas and five step-up micro-converters were designed, manufactured and tested. The microstrip rectenna has a unique design with a geometrical area of 36 cm2 and high frequency to direct current power conversion efficiency of 17.5%–74% measured at 0.6 μW/cm2 to 55 μW/cm2 input power density in 860–890 MHz band and a large bandwidth of 800 MHz-13GHz range. The micro-converters were supplied from the rectenna array output with 300mV–1200mV, charging each one 3 V/6 mAh accumulator. The DC to DC conversion efficiency of the micro-converters falls in 43%–59% range. Our micro-converter has an average increased conversion efficiency of about 15% higher than any published solutions, measured below one miliwatt input power. Our micro-converter can be used for other energy harvesting devices such as low light indoor photovoltaic cells or ultra low power thermoelectric generators.