Abstract
On-body transmission represents a challenge due to human body shadowing. This paper proposes a Sommerfeld-Goubau single-wire transmission line (SWTL) implemented using electronic textiles for low-loss on-body links up to millimeter-wave frequencies, overcoming the spherical spreading loss and on-body absorption. The SWTL is fabricated using a conductive thread suitable for embroidery on textiles. A compact tapered launcher is implemented on a flexible polyimide substrate to excite the surface mode along the SWTL. In space, a 3 m-long line maintains a forward transmission over −10 dB between 1 and 3 GHz. The SWTL link is characterized for different body parts showing under 20 dB insertion loss with a 1 cm air gap. Across the torso, a forward transmission over −20 dB is maintained from 0.5 to 2.5 GHz, which represents at least 20 dB improvement over two antennas, of larger dimensions, over-the-air. Directly on-skin, the SWTL can be used around 1 GHz with an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$S_{21}$ </tex-math></inline-formula> over −25 dB, over 50 dB improvement over two on-skin antennas. At 50 GHz, the shielded SWTL exhibits an ultra-low on-body attenuation around 0.11 dB/mm, a four-fold improvement over a microstrip line on the same substrate. It is concluded that SWTLs can enable ultra high-speed future body area networks.
Highlights
B ODY Area Networks (BANs) have attracted significant research interest for reliably connecting and powering wearable devices [1]–[3], often implemented using flexible and textile-based materials [4]–[7]
UWB communication between tional cross-talk between co-located transceivers, such crosson-body devices could be realized using the proposed single-wire transmission line (SWTL), talk effects between co-located surface wave lines have not owing to the uniform phase response and the broadband S21 been investigated in previous works dealing with surface-wave improvement over the unconnected OTA antennas
The use of surface wave on-body links for lowloss ultra-broadband transmission up to 50 GHz was proposed based on a textile SWTL
Summary
B ODY Area Networks (BANs) have attracted significant research interest for reliably connecting and powering wearable devices [1]–[3], often implemented using flexible and textile-based materials [4]–[7]. The additional advantage of on-body RF links is enabling high data-rate communication between wearables located on the same body or garment [18]. High channel gain wireless links [21] and low-loss textile-based waveguides [22] are required to enable high data-rate communication on-body. Utilizing bodyconfined electric or magnetic fields under 100 MHz, low-loss links can be realized between multiple on-body devices for transferring data and power [2], [10], [25]. SWTLs have not been applied to wearable applications, and the interaction of surface-waves with the human body has not been investigated or compared to unconnected propagation between on-body antennas. A wearable low-loss mmWave on-body link supported by a shielded e-textile SWTL is proposed for the first time, demonstrating a four-fold improvement over a state-ofthe-art textile-based microstrip line.
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