Self-Calibrating Meniscus-Removal Liquid Permittivity Measurements in Q-Band Semi-Open Waveguide Cell

We introduce a novel broadband calibration-independent meniscus-removal transmission/reflection method for liquid permittivity measurements in a semi-open rectangular waveguide using a vector network analyzer (VNA). We utilize scattering matrices measured for at least five different volumes of the liquid tested to eliminate the effects of the systematic error terms introduced by the VNA with a test fixture and a reproducible meniscus shaping the liquid sample surface. This approach provides precise both, the height, and the permittivity of the sample solely from electrical measurements. The method is validated with distilled water measurements done in Q-band (33-50 GHz).