Research Article Design of a Circularly Polarized Galileo E6-Band Textile Antenna by Dedicated Multiobjective Constrained Pareto Optimization Arnaut Dierck, 1 Frederick Declercq, 1 Thomas Vervust, 2 and Hendrik Rogier 1 1 Electromagnetics Group, Department of Information Technology, iMinds-Ghent University, 9000 Ghent, Belgium 2 Centre for Microsystems Technology, IMEC-Ghent University, 9000 Ghent, Belgium Correspondence should be addressed to Arnaut Dierck; arnaut.dierck@intec.ugent.be Received 28 July 2014; Revised 17 November 2014; Accepted 18 November 2014 Academic Editor: Diego Caratelli Copyright © 2015 Arnaut Dierck et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Designing textile antennas for real-life applications requires a design strategy that is able to produce antennas that are optimized over a wide bandwidth for ofen conficting characteristics, such as impedance matching, axial ratio, efciency, and gain, and, moreover, that is able to account for the variations that apply for the characteristics of the unconventional materials used in smart textile systems. In this paper, such a strategy, incorporating a multiobjective constrained Pareto optimization, is presented and applied to the design of a Galileo E6-band antenna with optimal return loss and wide-band axial ratio characteristics. Subsequently, diferent prototypes of the optimized antenna are fabricated and measured to validate the proposed design strategy. 1. Introduction With the advent of ubiquitous computing, the need for ever smaller, cheaper, and more powerful electronic devices has increased signifcantly. Smart fabrics and interactive textiles (SFIT) ofer great potential to increase the func- tionality in a wide gamut of applications at a low cost, both in terms of price and space. From healthcare to civil services, by using suitable materials such as (conductive) textiles, foams, and 3D fabrics to realize active circuits and antennas, electronic systems can be unobtrusively integrated into clothing, implementing features that would otherwise require additional, ofen cumbersome, devices that have to be carried around [1–8]. For rescue workers, having access to services such as positioning, victim localization, vital signs monitoring, and environmental hazard sensing can mean the diference between life and death. Replacing the traditional, rigid, hand-held devices by electronics directly integrated into the wearer’s garment, however, does not come without specifc design challenges. Te placement of the wearable systems inside of a garment makes them susceptible to infuences of the proximity of the body. Moreover, the foam and fabric substrates give rise to additional losses and their fexibility, while being indispensable for a conformal integration into clothing makes the antennas vulnerable to bending, potentially afecting their performance [9, 10]. Additionally, the of-the-shelf foam/textile materials, which have not been specifcally designed and fabricated as radio frequency (RF) substrates, can exhibit high variations on their RF properties when looking at diferent product batches. Tese variations can cause an unwanted shif in the antenna frequency response, which can reduce performance in the required frequency range. As wearable applications ofen require a low-profle antenna, the antenna thickness, mainly determined by the height of the antenna substrate, is a key aspect in the design process. A thinner antenna substrate ofers a more comfortable integration into the garment but, at the same time, limits the margins the designer can introduce to ruggedize the antenna to material variations by increasing the antenna bandwidth. In order to meet the stringent requirements for modern applications, in terms of both performance and wearability, it is important not only to base the design on a suitable antenna topology that is subsequently optimized in view of the diferent design objectives, but also Hindawi Publishing Corporation International Journal of Antennas and Propagation Volume 2015, Article ID 895963, 7 pages http://dx.doi.org/10.1155/2015/895963