HARVESTING MICROWAVE SIGNAL POWER FROM THE AMBIENT ENVIRONMENT

Abstract

- To harvest microwave frequencies in the ambient environment and convert into DC is presented in this paper. The RF harvester replaces a dedicated RF source which is used in an applications like wireless sensor networks to battery operated wireless handheld devices. The focus of work is divided into two parts. The first is to design a compact planar prototype microstrip patch antenna using HFSS for the frequencies of 900&1800MHz (GSM band), 1575MHz (GPS band) and 2.4GHz (ISM band). Antenna is fabricated using MITS PCB prototype machine and tested in VNA. Results obtained from the VNA indicates -30dB and -35dB for GSM 900& 1800 MHz, -15dB for GPS 1575 MHz band and -28dB for ISM 2.4GHz band. Second part consists of RF circuit model includes matching and rectification unit which determines the RF to DC conversion efficiency up to 60%. Voltage doubler RF rectification circuit using schottky diode is designed in ADS and it is tested practically. A lumped T type matching network is implemented to provide a proper impedance match.