Wearable substrate-integrated waveguide with embroidered vias

A textile substrate-integrated waveguide structure using embroidered silver-coated yarn vias as side walls is presented in this paper. This straightforward fabrication technique allows the precise realization of complex arbitrary patterns for guiding electromagnetic waves in wearable applications. The concept retains properties of conventional waveguides such as low-loss propagation and shielding, however in a low profile and flexible implementation. A two-port back-to-back structure with coaxial feeds operating within 5-6 GHz has been designed and manufactured to demonstrate the principle. The realized prototype exhibits an insertion loss of 2.3 dB including two coaxial transitions and a waveguide length of 2.5 wavelengths. Measuring the waveguide performance shows that the structure is very robust to bending, compression and torsion. This opens perspectives for further steps such as efficiency improvements and investigation of more complex waveguide structures including flexible bends and feeds for wearable applications.