Arnaut Dierck

A Wearable Active Antenna for Global Positioning System and Satellite Phone

A wearable multiband circularly polarized active antenna is presented for use in Global Positioning System and Iridium satellite phone applications. The square patch antenna is constructed using flexible foam and fabric substrates and conductors etched on thin copper-on-polyimide films. The feed substrate integrates a compact low-noise amplifier chip directly underneath the antenna patch. The antenna performance is studied under bending conditions and in the presence of a human body. The active antenna exhibits a gain higher than 25 dBi and a 3 dB axial ratio bandwidth exceeding 183 MHz in free-space conditions and is robust to bending and on-body placement.

Textile Microwave Components in Substrate Integrated Waveguide Technology

Although substrate integrated waveguide (SIW) technology is well established for the fabrication of microwave circuits on rigid printed circuit boards, and the first implementations of textile SIW antennas have recently appeared in literature, up to now, no complete set of SIW microwave components has been presented. Therefore, this paper describes the design, manufacturing, and testing of a new class of textile microwave components for wearable applications, implemented in SIW technology. After characterizing the adopted textile fabrics material in terms of electrical properties, it is shown that folded textile SIW components, such as interconnections, filters, and antennas form excellent building blocks for wearable microwave circuits, given their low profile, flexibility, and stable characteristics under bending and in proximity of the human body. Hence, they allow the full exploitation of the large area garments offered for the deployment of wearable electronics. Besides SIW interconnections, a folded textile SIW filter operating at 2.45 GHz is designed and tested. The filter combines excellent performance in the band of interest with good out-of-band rejection, even when accounting for the tolerances in the fabrication process. Finally, a folded SIW cavity-backed patch antenna is fabricated and experimentally verified in realistic operating conditions.

A Stochastic Framework for the Variability Analysis of Textile Antennas

A novel framework to accurately quantify the effect of stochastic variations of design parameters on the performance of textile antennas is developed and tested. First, a sensitivity analysis is applied to get a rough idea about the effect of these random variations on the textile antennas performance. Next, a more detailed view is obtained by a generalized polynomial chaos technique that accurately quantifies the statistical distribution of the textile antennas figures of merit, for a given range over which geometry and material parameters vary statistically according to a given distribution. The method is validated both for a simple inset-fed patch textile microstrip antenna and for a dual-polarized textile antenna. For the latter, the probability density function corresponding to its most sensitive design parameter, being the width, is experimentally estimated by means of measurements performed on 100 patches. A Kolmogorov-Smirnoff test proves that, for all considered examples, the results are as accurate as those obtained via Monte Carlo analysis, while the new technique is much more efficient. Indeed, speedups up to a factor 1667 are demonstrated.

Review of active textile antenna co-design and optimization strategies

This paper describes the challenges that arise in active wearable textile antenna design and optimization. After a short introduction, design strategies for two cases with different needs are discussed and examples are given for each design strategy. In the first case, a low-noise amplifier is connected directly to a 2.45 GHz ISM-band antenna by optimizing the antenna impedance to match the low-noise amplifier input impedance for optimal noise performance. In the second case, an aperture-coupled GPS antenna incorporating a discrete 50 Ω hybrid coupler is linked to a low-noise amplifier by means of a matching network to match the 50 Ω hybrid coupler port to the low-noise amplifier impedance for optimal noise performance.

An active wearable dual-band antenna for GPS and Iridium satellite phone deployed in a rescue worker garment

An active wearable dual-band circularly polarized microstrip patch antenna for Global Positioning System and Iridium satellite phone applications is presented. It is constructed using flexible foam and fabric substrates, combined with copper-on-polyimide film conductors. A low-noise amplifier chip is integrated directly underneath the antenna patch. The antennas performance is examined under bending and on-body conditions. The active antenna gain is higher than 25 dBi and the 3dB axial ratio bandwidth exceeds 183 MHz in free-space conditions. The antenna performance is robust to bending and on-body placement.

Design of a Circularly Polarized Galileo E6-Band Textile Antenna by Dedicated Multiobjective Constrained Pareto Optimization

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 often conflicting characteristics, such as impedance matching, axial ratio, efficiency, 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, different prototypes of the optimized antenna are fabricated and measured to validate the proposed design strategy.