For the application of geometrically-induced THz
surface wave technology for communication and sensing, a critical analysis of the propagation characteristics (i.e. dispersion and
attenuation) for different textured surfaces should be studied and
benchmarked. For the broadband characterisation of archetypal
textured surfaces (e.g. corrugated plane, two-dimensional array
of blind holes and bed of nails) supporting THz transverse
magnetic (i.e., p-polarized) surface waves, we employ timedomain spectroscopy and edge-diffraction coupling methods.
Measurements of laser micromachined prototypes demonstrate
strong frequency-dependent dispersion and the large impact that
surface roughness of the order of few µm has on the path loss,
increasing it by a factor ranging from 1.6 to 4.3 compared to
smooth textured surfaces. Together with numerical modelling,
we disentangle all loss mechanisms (namely, ohmic, scattering,
propagation divergence and phase mismatch) and highlight the
challenge of loss estimation due to surface roughness in highly
confined THz surface waves.