RF conversion for power supply

Abstract

A study on Radio frequency (RF) conversion to DC voltage has been undertaking. RF was generated from mobile phone of about 900MHz and harvested by a circuit called rectenna. The rectenna consists of antenna and rectifier. A simple helical antenna was used. The rectifier was just a voltage multiplier which converts the RF to DC voltage and at the same time its multiplied the voltage magnitude. Two types of voltage multiplier were used. One is a simple multiplier which multiply the voltage by two. The other one was a ladder type which can multiply more depending on the number of ladders used. The rectenna arranged either series or parallel was study in order to determine the best reception. A single rectenna, two array rectenna, 3 array rectenna and 4 array rectenna were tested.The next stage was the DC –DC step up converter. An IC MAX 575 was used in order to convert the voltage to a stable 5V DC. It was found that the more the array, the more will be the voltage harvested. A voltage of 3V can be obtained. The DC –DC step up converter was able to convert 3V to 5V.