A Six-Port Reflectometer Operating at Submillimeter Wavelengths

The frequency range of six-port reflectometry is extended to the range of submillimeter waves by a new quasi-optical six-port device consisting of quasi-optical components such as beam-splitters, reflectors and lenses. The complex reflection coefficient is determined in terms of simple power measurements using commercial r.f. power meters including X-band waveguide thermistor heads. The uncertainty of measurement is ± 0.02 for the absolute value and ±2° for the phase angle of the reflection coefficient. From the reflection coefficient measurements, the complex permittivity of solid low-loss dielectrics could be determined with small uncertainty of measurement at some fixed frequencies of about 390 GHz.