Browsing by Author "Tavares, Jorge"
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- Antennas and circuits for ambient RF energy harvesting in wireless body area networksPublication . Barroca, Norberto; Saraiva, Henrique M.; Gouveia, Paulo T.; Tavares, Jorge; Borges, Luís M.; Velez, Fernando J.; Loss, Caroline; Salvado, Rita; Pinho, Pedro; Gonçalves, Ricardo; Carvalho, Nuno Borges; Chavez-Santiago, Raul; Balasingham, IlangkoIn this paper, we identify the spectrum opportunities for radio frequency (RF) energy harvesting through power density measurements from 350 MHz to 3 GHz. The field trials have been performed in Covilhâ by using the NAKDA-SMR spectrum analyser with a measuring antenna. Based on the identification of the most promising opportunities, a dual-band band printed antenna operating at GSM bands (900/1800) is proposed, with gains of the order 1.8-2.06 dBi and efficiency 77.6-84%. Guidelines for the design of RF energy harvesting circuits and choice of textile materials for a wearable antenna are also discussed. Besides, we address the guidelines for designing circuits to harvest energy in a scenario where a wireless body area network (WBAN) is being sustained by a TX91501 Powercasf® RF dedicated transmitter and a five-stage Dickson voltage multiplier responsible for harvesting the RF energy. The IRIS motes, considered for our WBAN scenario, can perpetually operate if the RF received power attains at least -10 dBm.
- Application of Wireless Sensor Networks to AutomobilesPublication . Tavares, Jorge; Velez, Fernando J.; Ferro, João MiguelSome applications of Wireless Sensor Networks (WSNs) to the automobile are identified, and the use of Crossbow MICAz motes operating at 2.4 GHz is considered together with TinyOS support. These WSNs are conceived in order to measure, process and supply to the user diverse types of information during an automobile journey. Examples are acceleration and fuel consumption, identification of incorrect tire pressure, verification of illumination, and evaluation of the vital signals of the driver. A brief survey on WSNs concepts is presented, as well as the way the wireless sensor network itself was developed. Calibration curves were produced which allowed for obtaining luminous intensity and temperature values in the appropriate units. Aspects of the definition of the architecture and the choice/implementation of the protocols are identified. Security aspects are also addressed.
- Application of Wireless Sensor Networks to the AutomobilePublication . Tavares, Jorge; Velez, Fernando José; Ferro, João MiguelSome applications of Wireless sensor networks (WSNs) to the automobile are identified, and the use of MICAz motes operating at 2.4GHz is considered together with TinyOS support. These WSNs are being conceived in order to measure, process and supply to the user diverse types of information during an automobile journey. Examples are acceleration and fuel consumption, identification of incorrect tire pressure, verification of illumination, and evaluation of the vital signals of the driver. A survey on WSNs concepts is presented, and the wireless sensor network itself (transmitter/receiver/control board) is developed. Aspects of the definition of the architecture and the choice/implementation of the protocols are identified. Security aspects are also addressed, and solutions are proposed.
- Application of Wireless Sensor Networks to the AutomobilePublication . Tavares, Jorge; Velez, Fernando José; Ferro, João MiguelSome applications of Wireless sensor networks (WSNs) to the automobile are identified, and the use of MICAz motes operating at 2.4GHz is considered together with TinyOS support. These WSNs are being conceived in order to measure, process and supply to the user diverse types of information during an automobile journey. Examples are acceleration and fuel consumption, identification of incorrect tire pressure, verification of illumination, and evaluation of the vital signals of the driver. A survey on WSNs concepts is presented, and the wireless sensor network itself (transmitter/receiver/control board) is developed. Aspects of the definition of the architecture and the choice/implementation of the protocols are identified. Security aspects are also addressed.
- Design and evaluation of multi-band RF energy harvesting circuits and antennas for WSNsPublication . Borges, Luís M.; Barroca, Norberto; Saraiva, Henrique M.; Tavares, Jorge; Gouveia, Paulo T.; Velez, Fernando J.; Loss, Caroline; Salvado, Rita; Pinho, Pedro; Gonçalves, Ricardo; Carvalho, Nuno Borges; Chavez-Santiago, Raul; Balasingham, IlangkoRadio frequency (RF) energy harvesting is an emerging technology that will enable to drive the next generation of wireless sensor networks (WSNs) without the need of using batteries. In this paper, we present RF energy harvesting circuits specifically developed for GSM bands (900/1800) and a wearable dual-band antenna suitable for possible implementation within clothes for body worn applications. Besides, we address the development and experimental characterization of three different prototypes of a five-stage Dickson voltage multiplier (with match impedance circuit) responsible for harvesting the RF energy. Different printed circuit board (PCB) fabrication techniques to produce the prototypes result in different values of conversion efficiency. Therefore, we conclude that if the PCB fabrication is achieved by means of a rigorous control in the photo-positive method and chemical bath procedure applied to the PCB it allows for attaining better values for the conversion efficiency. All three prototypes (1, 2 and 3) can power supply the IRIS sensor node for RF received powers of -4 dBm, -6 dBm and -5 dBm, and conversion efficiencies of 20, 32 and 26%, respectively.
- Developing Sustainable Communication Interfaces Through Fashion DesignPublication . Loss, Caroline; Salvado, Rita; Lopes, Catarina; Pinho, Pedro; Gonçalves, Ricardo; Velez, Fernando J.; Saraiva, Henrique Morais; Tavares, Jorge; Barroca, Norberto; Borges, Luís M.The recent technological developments made electronic devices become imperative and indispensable, being present in our daily routines, all over the world. But, the continuous exposition of people to the electromagnetic radiation might cause illness. Electrosmog is the invisible electromagnetic radiation that results from the usage of electric equipment and wireless technologies. Some studies present electro sensibility as a contemporary illness affecting more and more people. This paper analyses some of the challenges this reality puts to the fashion design and how textile materials may be used to protect the human body against the harmful radiation and to develop smart cloths incorporating textile antennas able to capture these radiations and feed low-frequency devices. Thus, one considers the notion of “Transparent Sustainability” and the search for the smart energy explorations of/or in the human body. This way, the association of fashion design and technology can transform the garment in a sustainable communication interface.
- Experimental Characterization of Wearable Antennas and Circuits for RF Energy Harvesting in WBANsPublication . Saraiva, Henrique Morais; 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, RitaField 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.
- Identification of the Opportunistic Radio Frequency Bands for Energy Harvesting in Wireless Body Area NetworksPublication . Barroca, Norberto; Borges, Luís M.; Tavares, Jorge; Velez, Fernando J.; Chávez-Santiago, Raul; Balasingham, I.This paper presents the spectrum opportunities for radio frequency (RF) energy harvesting enabling to power supply future wireless body area networks (WBANs). The field trials have been performed in Covilhã by using the NARDA-SMR spectrum analyser with measuring antenna. Besides, this work addresses physical (PHY), medium access control (MAC) and network layer design aspects, by considering cognitive radio (CR) opportunities by means of the identification of the most promising bands.