Textile Antenna for Electromagnetic Energy Harvesting for GSM900 and DCS1800 bands Ricardo Gonc¸alves1,2 and Nuno B. Carvalho1,2 1
P. Pinho1,3 , Caroline Loss4 and Rita Salvado4 3
Instituto de Telecomunicac¸o˜ es, Aveiro, Portugal 2 Universidade de Aveiro, Aveiro, Portugal
[email protected],
[email protected]
4
Abstract—Energy harvesting is the process by which energy is derived from external sources captured, and stored for small, wireless autonomous devices, like those used in wearable electronics and wireless sensor networks. This paper presents the design of two textile antenna suitable to harvest energy in the GSM900 and DCS 1800 bands. The antennas gain, are of the order 2 dBi and efficiency 80%.
I. I NTRODUCTION Energy harvesting will allow for recharging batteries or super capacitors, and will have a great impact on the lifetime of wireless sensor networks (WSNs). This has particular importance as the network size increases and the replacement of the batteries is not always practical. The common sources of energy harvesting include the following [1]: mechanical, thermal, electromagnetic, natural and human motion. Nowadays, energy harvesting devices efficiently and effectively capture, accumulate and store energy, to power up the sensor nodes for short periods of time, in order to perform helpful tasks. However, in a not too distant future, they will enable to supply all the nodes of WSN without the need of replacement of batteries. This energy can be used continuously to increase the battery charge or prevent power leakage. In [2], the authors present the state-of-the-art of energy harvesting techniques for low power systems such as power conversion, power management, and battery charging, as well as the advances in energy harvesting from vibration, thermal, and radio frequency (RF) sources. Prototypes for the energy harvesting from the ambient RF spectrum have been proposed in [3], [4], enabling to power supply low-power systems. In the context of wireless body area networks (WBAN) electromagnetic energy harvesting is accomplished by using wearable antennas allowing for power supply the sensor nodes [5]. The remaining of this paper is organized as follows. Section II presents the motivation of our work as well as the average received power for different RF sources. Section III describes the design of single and dual band antennas for collecting RF energy. Finally, Section IV draws the main conclusions. II. RF E NERGY S CAVENGING AND R ECEIVED P OWER Nowadays, RF energy is currently broadcast from billions of radio transmitters (e.g., mobile communications base stations and television/radio stations) that can be collected from the
978-1-4673-5317-5/13/$31.00 ©2013 IEEE
Inst. Sup. Eng. Lisboa - ISEL, Lisboa, Portugal Universidade da Beira Interior, Covilh˜a, Portugal
[email protected],
[email protected],
[email protected]
ambient. Our vision is that this energy holds a promising future for power supply wireless electronics devices. One of the contributions from this work is the measurements of the electromagnetic spectrum availability from 350 MHz to 3 GHz. The field trials were performed by using the NARDASMR [6] and PROLINK 4-4C signal meter [7], as shown in [8], in different locations, which led to the average results depicted in Figure 1. From which, we conclude that the best set of frequency bands for energy harvesting is the mobile phone bands.
Fig. 1.
Average received power for all measurements.
III. A NTENNAS FOR RF E NERGY H ARVESTING Considering the previous analysis regarding the best frequencies for energy harvesting, it is proposed in this section, a possible implementation of two textile antennas suitable to be introduced within clothes for body worn applications, a single band antenna to harvest in the GSM900 band and a dual band antenna to harvest in GSM900 and DCS1800. The proposed antennas design is shown in Figure 2. Table I presents the corresponding dimensions. A Cordura cloth type was considered for the substrate, it presents a permittivity (r ) of approximately 1.9 and a loss tangent (tan δ) of 0.0098, having a relative height of 0.5 mm. For the conductive sections of the antenna an electrotextile (Zelt), with an electric conductivity of 1.75105 S/m was considered. The return loss obtained from numerical simulations of the proposed antennas is presented in Figure 3. From which is observed that these antennas present an operating frequency
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(a) Fig. 2.
Fig. 4. Simulated radiation pattern for the proposed antennas in the YZ plane (dashed) and XZ plane (solid) for single band (black), dual band at 900 MHz (green) and dual band at 1800 MHz (blue).
(b) Proposed antennas design.
TABLE I P ROPOSED ANTENNAS DIMENSIONS .
Single band
Dual band
Parameter L, Lgnd Lf, Lm, Lfx W, Wf, Wm L, Lgnd, Lf, Lfx Lm1, Lm2, gap, W Wf, Wm1, Wm2, Wm3, Wm4
allied with 82% and 77.6% radiation efficiency for the lowest and highest frequency bands, respectively.
Dimension [mm] 120, 100 78, 12, 26 80, 1.5, 55 120, 100, 78, 30 12, 5, 31, 80 1.5, 31, 21, 8, 4
range capable of completely covering the GSM900 (880-960 MHz) and the DCS1800 (1710-1880 MHz).
IV. C ONCLUSION Energy harvesting can significantly increase the lifetime of WSN and eliminate or reduce the need for battery replacement, reducing costs and failures of sensors. In this paper we have analysed the development of a wearable antenna that will enable to charge low-power devices, as well as extending the lifetime of tiny devices by using electromagnetic energy harvesting. Moreover, since radio frequencies, especially mobile phone frequencies, are present in almost everywhere, some devices have the possibility to be continuously charged, avoiding power fail situations. As future work we intended to evaluate the human body presence in the performance of the antenna and create a flexible and wearable antenna, with the described characterization. V. ACKNOWLEDGEMENTS The authors acknowledge the Portuguese FCT/MCTES for financing the project PTDC/EEA-TEL/ 122681/2010PROENERGY-WSN-Prototypes for Efficient Energy SelfSustainable Wireless Sensor Networks.
Fig. 3.
R EFERENCES
Simulated return loss of the single- and dual-band antennas.
Since the privileged direction of signal reception is not known, the best possible radiation pattern for the antenna is an omnidirectional radiation. The obtained radiation patterns, based on numerical simulations, in the YZ and XZ planes (see Figure 2), is depicted in Figure 4. From which one can observe that these are clearly omnidirectional. In energy harvesting applications, to achieve the best performance possible, the antenna should present the highest gain and the highest efficiency possible. The gain obtained, from numerical simulation, for the single band antenna comprise a gain of about 2.05 dBi, allied with 84% radiation efficiency, which are adequate results for this type of antenna. For the dual band antenna the gains are about 1.8 dBi and 2.06 dBi
[1] F. Yildiz, D. Fazarro, and K. Coogler, “The green approach: Self-power house design concept for undergraduate research,” Journal of Industrial Technology, vol. 26, pp. 1–10, 2010. [2] A. Harb, “Energy harvesting: State-of-the-art,” Renewable Energy, vol. 36, pp. 2641–2654, 2011. [3] S. Kitazawa, H. Ban, and K. Kobayashi, “Energy harvesting from ambient rf sources,” in in Proc. of IEEE MTT-S International Microwave Workshop Series on Innovative Wireless Power Transmission: Technologies, Systems, and Applications (IMWS-IWPT), Japan, 2012. [4] H. C. Sun, Y.-X. Guo, M. He, and Z. Zhong, “Design of a highefficiency 2.45-ghz rectenna for low-input-power energy harvesting,” IEEE Antennas Wireless Propag. Lett., vol. 11, pp. 929–932, 2012. [5] J. S. Bellon, M. Cabedo-Fabres, E. Antonino-Daviu, M. FerrandoBataller, and F. Penaranda-Foix, “Textile mimo antenna for wireless body area networks,” in Proc. of the 5th European Conference on Antennas and Propagation (EuCAP), Italy, 2011. [6] http://www.narda-sts.com/cockpit/index.php?mp=Home, April 2012. [7] http://www.e-projects.ubi.pt/proenergy-wsn, November 2012. [8] http://www.promaxprolink.com/prolink/prolink4.htm, October 2012.
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