Abstract
We propose a Bluetooth Low Energy (BLE) beacon that operates entirely on harvested energy from dual ISM-band RF sources with aid from photovoltaics. Indoor RF power can be harvested from Wi-Fi devices in both 2.4 GHz and 5 GHz bands. Indoor photovoltaic power, while often too low to be considered useful, can be used as biasing current to improve the efficiency of the RF harvester. The proposed harvester performs impedance matching in two bands and maximum power point tracking and stores energy in a solid-state battery and a supercapcitor. Our implementation of the energy-neutral BLE beacon can broadcast every 45 seconds at the input power of 15 dBm. In terms of harvested power, our proposed system harvests more power from both bands in a miniature, lowcost circuit than the state-of-The-Art from three channels in a single band. This work represents a step towards enabling a class of IoT systems to operate entirely on harvested indoor RF power.