Abstract
This paper presents spectrum opportunities for radio frequency (RF) energy harvesting identified through power density measurements from 350 MHz to 3 GHz. The field trials have been performed in two different cities (Covilhã and Lisbon), by using the NARDA-SMR spectrum analyser with measuring antenna, and the Signal Hound spectrum analysers, respectively. The scope of our research considers RF energy harvesting devices, enabling to convert RF energy to direct current (DC), providing an alternative source to power supply wireless sensor network (WSN) devices. Printed antennas, able to operate at GSM (900/1800) bands, are proposed with gains of the order of 1.8-2.06 dBi and efficiency 77.6-84%. Guidelines for the choice of textile materials for a wearable antenna are also provided.
Authors: Jorge Tavares, Norberto Barroca, Henrique M. Saraiva, Luís M. Borges, Fernando J. Velez, Caroline Loss and Rita Salvado, Pedro Pinho, Ricardo Gonçalves and Nuno Borges Carvalho