Low-Mode Low-Loss Waveguides and Open-Resonator Techniques at Submillimeter Wavelengths

A modified form of H-guide is investigated theoretically and experimentally. Attenuations < 1 dB/m are predicted. Guide characteristics are verified at 8 mm wavelength, and guide attenuation of 8 dB/m achieved at 1/3 mm wavelength. Open-resonator characteristics are investigated at 337 um using a HCN laser. Resonance spectra agree with theoretical predictions and Q factors up to 8 × 10⁴ achieved. Dielectric permittivity and loss-tangent values are obtainable from spectra changes. This work sponsored by United Kingdom National Physical Laboratory.