Textile Microwave Components in Substrate Integrated Waveguide Technology

Abstract

Abstract-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-ofband 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. Index Terms-Cavity-backed antenna, folded waveguide, substrate integrated waveguide, textile material, wearable systems.

Circularly‐polarised cavity‐backed wearable antenna in SIW technology

“…This is mainly due to the presence of the SIW cavity, which prevents the excitation of surface waves. Some improvements were obtained with a cavity-backed patch antenna [16], in terms of radiation performance (with the radiation efficiency increased to 74%) and size of the component (size reduction of 43%).…”

“…The other resonant mode exhibits a similar field pattern, with a rotation of 90° around the z axis. Each of the two modes is able to generate a linearly-polarized radiated field (this operation principle, based on the use of a single mode, was adopted in previous works [16]). The concept is clarified by the field distribution on the radiating slot, shown in Fig.…”

“…For the design of the antenna, the electrical characteristics of the textile foam determined in [16] were used (εr = 1.45, tan δ = 0.017). The optimized geometrical dimensions are reported in Tab.…”

“…Several alternative textile antenna topologies were proposed in the last few years, aiming at the reduction of the antenna footprint. They include single band [11], [12] and dual band [13], [14] half-mode or quarter-mode [15] substrate integrated waveguide textile antennas, as well as folded [16] and folded half-mode SIW cavity-backed antennas [17].…”

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

“…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.…”