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A very realistic example of realization is shown in Figure 3, in which you can see the geometry of the excitation circuit composed of a signal splitter (one to three), three planar transmission lines of different lengths, and three similar antennas exhibiting different spatial orientations. In practice, to allow 360˚ radiation coverage, two groups of antennas are required — one on the left side and one on the right side, as shown in Figure 2. Performance To evaluate the performance of the Giante WBAN concept, several experimental characterizations were conducted. They focused on matching, radiation pattern, and communication range. The Giante antenna was designed for the frequency band between 2.0 and 2.1 GHz, and it uses simple dipole antennas as radiating elements. The measured reflection coef- ficient shown in Figure 4 is very satisfactory, as it is greatly below -15 dB over a very large band — roughly between 2.0 and 2.4 GHz. The simulated and measured radiation patterns are shown in Figure 5. The measurements were conducted in an anechoic chamber. You can see there is good agree- ment between simulation and measurement even if, for some directions, more important differences exist. Such mismatches are mainly due to inaccuracies of the measurement setup. The SAR of such an antenna was also studied. Simulation on CST allows the determination of such a parameter. The most interesting result is the value of SAR under 1 W power injected: SAR local for 10 g of tissue = 1.24 W/Kg < SAR max (2 W/Kg for the head and 4 W/Kg for the members). This SAR is three times lower than the maximum allowed by regulations. The last experimental characterization performed was the measurement of the communication range in a real, free- space environment. Communication ranges exceeding 1400 m were measured in all directions between two military vests equipped with the Giante WBAN concept (power used = 1 W). Other experiments in real environments were conduct- ed in forests and dense urban zones, and they demonstrated communication ranges exceeding 500 m. Conclusion In this paper we presented a new concept of a wearable antenna that can easily integrate into clothing. The proposed concept, recently patented, is based on the exploitation of the interference phenomena between electromagnetic fields radiated from a group of antennas, which form spatial regions with a low level of electromagnetic field. Moreover, this concept allows integrating the group of the antennas in the same planar design that includes the RF circuit to feed each antenna. The target circuit is essentially an architecture of transmission lines and passive elements, such as power dividers. The Giante WBAN concept was demonstrated experimentally at an operating frequency around 2 GHz, and good performances were obtained — particularly in radiation coverage and communication ranges, while exhibiting a low level of SAR. It is worth noting the excellent ergonomics of this concept, as well as its high compatibility with digi- tal printing technologies and the potential of its realization directly on tissue or fabric. Acknowledgement This concept was developed within the Giante Project funded by the RAPID-DGA program. The authors would like to thank the DGA for its funding and Pierre- François Louvigne for his continued support and clever advice. References [1] Y. Hao, A. Alomainy, P. Hall, Y. Nechayev, C. Parini, and C. Constantinou, Antennas and Propagation for Body-Centric Wireless Communications, Artech House, 2006. [2] "Voxel Import Applications." CST. CST, n.d. Web: https://www.cst.com/Applications/ TopicApplications?topicId=178. [3] T. Andriamiharivolamena, P. Lemaitre-Auger, D.Kaddour, S.Tedjini, F.Tirard, J.Mourao, "Bending and crumpling effects on a wearable planar monopole antenna," Antenna Technology and Applied Electromagnetics (ANTEM), 2012. 15th International Symposium on, vol., no., pp.1, 4, 25-28. June 2012. Feature Electronic Military & Defense Annual Resource, 4th Edition 34 Figure 5: Measured radiation pattern of an antenna group in the presence of the human body: (a) Copolarization gain, (b) Cross- polarization gain. For the simulation results, the type of antenna used is a dipole, and a discrete port feeds each dipole. Figure 4: Measured reflection coefficient of an antenna group Professor Smail Tedjini (smail.tedjini@grenoble-inp.fr) received his Ph.D. in physics from Grenoble Institute of Technology in 1985. Founder of the institute's LCIS Laboratory, he currently researches wireless RF systems, RFID, and wearable technologies. Author of 250 publications, he is a senior member of the IEEE and chair of URSI Commission D since 2011.