Improving the Multi-GBPS Signal Integrity Using Goubau-Inspired Hybrid Surface Wave Lines

Single-wire transmission lines (SWTL) guiding conformal surface waves are attractive for low-loss broadband non-line-of-sight (NLOS) links. However, they suffer from a fundamental limitation that is an HF stop-band, between 1 and 100 MHz, unresolved across state-of-the-art implementations. Here, a loosely-coupled 2-wire surface-wave line structure is proposed, inspired by the Goubau SWTL, and is evaluated from analytical impedance calculations to practical signal integrity measurements. The line is fed using two flexible coplanar waveguide (CPW) tapered Vivaldi launchers, with an additional ground wire is incorporated. The proposed structure reduces the maximum insertion loss from over 40 dB to under 20 dB, lowering the rejection compared to standard Goubau lines, with under 0.3 dB/cm attenuation under 4.5 GHz. Digital signalling is measured up to 3.6 GBPS through eye diagrams, standard and Manchester (IEEE 802.3)-encoded, showing successful communication. The line is validated in a wearable application, showing the first multi-GBPS wearable experimental demonstration.