Wearable textile antenna in substrate integrated waveguide technology

Abstract

A novel wearable substrate integrated waveguide antenna fabricated entirely from textile materials is presented. The cavity-backed slot antenna operates in the 2.45 GHz industrial, scientific and medical band, for short range communication between rescue workers. A prototype of the antenna was fabricated and tested: good performance was obtained in terms of input matching and radiation pattern. Moreover, measurements performed on the antenna after bending and integration into clothing indicate high robustness against deformation and low influence of the human body on antenna performance, making the design well-suited for on-body use.Introduction: The design of wearable components and antennas for wireless applications received significant attention [1] in the past decade. In particular, localization and tracking of fire-fighters in rescue operations, as well as communication in critical conditions, require lowcost and efficient systems that are comfortable to wear. Therefore, components and systems should be low-profile, light-weight and mechanically flexible, and the adopted substrates need to be flame resistant and water repellent. The textile fabrics typically applied in firefighter garments represent good candidates for implementing antennas that are suitable for integration into protective garments. A variety of patch antennas on textile, operating in the 2.4-2.4835 GHz industrial, scientific and medical (ISM) band, were proposed [1]. These antennas require a sufficiently large ground plane to limit the influence of the human body on the antenna's radiation characteristics. In addition, antenna performance should remain stable when the textile patch is subjected to bending [2]. In this Letter, a textile cavity-backed slot antenna in substrate integrated waveguide (SIW) technology is presented. To the authors' best knowledge this is the first implementation of a microwave SIW structure with textile materials. Cavity-backed antennas offer several advantages, such as suppression of unwanted surface waves and lower sensitivity for on-body operation, as well as a high front-to-back ratio [3]. SIW technology was chosen as a simple cost-effective fabrication process, which is already well-developed for printed circuit boards [4]. Furthermore, it allows easy integration of passive and active components onto the antenna [5], thus permitting the realization of complete systems on a textile carrier. An SIW cavity-backed slot antenna in textile materials was designed, fabricated and experimentally verified. The structure exhibits compact size and good flexibility, thanks to the use of eyelets as metalized holes implementing the SIW cavity. On-body measurements were performed, and the effect of bending was investigated to evaluate the antenna performance under realistic operating conditions.

Circularly‐polarised cavity‐backed wearable antenna in SIW technology

“…In an earlier work, the authors presented a linearlypolarized SIW cavity-backed slot antenna completely realized with textile materials for short-range communication between rescue workers [10]. Owing to its topology, the antenna ensures good electromagnetic performance (radiation efficiency 68%) even in proximity of the human body.…”

“…The realization of the first cavity-backed SIW antenna on textile [10] demonstrated the advantages of the combination of SIW technology with textile materials. Several alternative textile antenna topologies were proposed in the last few years, aiming at the reduction of the antenna footprint.…”

SIW antennas as hybrid energy harvesting and power management platforms for the internet of things

“…Hence, they prove that this topology is indeed very suitable as an integration platform, reducing the amount and length of interconnecting wires by exploiting its excellent antenna/environment isolation. The antenna's outstanding on-body performance was already demonstrated in [13]. 2) SFIT compact dual-polarized SIW antenna Fig.…”

“…The first topology under study is the wearable SIW cavity-backed textile slot antenna presented in [13], which is constructed entirely of textile materials for application in SFIT systems. This topology is depicted in Fig.…”

“…Their planar structure and low profile allow unobtrusive embedding in any surface, by reusing the dielectric material of the object itself, which is cost and area effective. It was recently proven that stable and high-performance SIW antennas can indeed be integrated into off-the-shelf textile fabrics and foams [13] [14] or into common floor and wall materials, such as cork [15]. More in particular, SIW cavity-backed antenna topologies [12] typically provide a high radiation efficiency and a good front-to-back ratio (FTBR), in line with energy autonomy systems.…”