Silver-Coated Teflon Tubes for Waveguiding at 1–2 THz

Realization of single-mode low-loss waveguides for 1.0–2.0 THz remains a challenging problem due to large absorption in most dielectrics and ohmic losses in metals. To address this problem, we investigate dielectric-lined hollow metallic waveguides fabricated by coating 1-mm diameter 38-μm-thick polytetrafluoroethylene tubes with silver. These waveguides support a hybrid HE₁₁ mode, which exhibits low attenuation and low dispersion. Quasi-single-mode propagation is achieved in the band of 1.0–1.6 THz, in which the hybrid HE₁₁ mode is supported by the waveguide. In this band, the experimentally measured loss is ~20 dB/m (~0.046 cm⁻¹), whereas the numerically computed loss is ~7 dB/m (~0.016 cm⁻¹). The difference is attributed to additional losses in the dielectric layer, which can be reduced by using alternative polymers.