Experimental Characterization of Wearable Antennas and Circuits for RF Energy Harvesting in WBANs

• Main Author: Saraiva, Henrique Morais
• Publication Date: 2014
• Other Authors: Borges, Luís M., Pinho, Pedro, Gonçalves, Ricardo, Chavez-Santiago, Raul, Barroca, Norberto, Tavares, Jorge, Gouveia, Paulo T., Carvalho, Nuno Borges, Balasingham, Ilangko, Velez, Fernando J., Loss, Caroline, Salvado, Rita
• Language: eng
• Source: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
• Download full: http://hdl.handle.net/10400.6/15169
• topic: Radio Frequency Energy Harvesting; Wireless Body Area Networks; Wearable Antenna; Voltage Efficiency

Field trials have been performed in Covilhã to identify the spectrum opportunities for radio frequency (RF) energy harvesting through power density measurements from 350 MHz to 3 GHz. Based on the identification of the most promising opportunities, a dual-band printed antenna was conceived, operating at GSM bands (900/1800), with gains of 1.8 and 2.06 dBi, and efficiency varying from 77.6 to 82%, for the highest and lowest operating frequency bands, respectively. In this paper, guidelines for the design of RF energy harvesting circuits and choice of textile materials for a wearable antenna are briefly discussed. Besides, we address the development and experimental characterization of three different prototypes of a five-stage Dickson voltage multiplier (with and without impedance matching circuit) responsible for RF energy harvesting. All the three prototypes (1, 2 and 3) can power supply the sensor node for RF received powers of 2 dBm, -3 dBm and -4 dBm, and conversion efficiencies of 6, 18 and 20%, respectively.