Permittivity measurements of lossy liquids in the range 26 110 GHz

We describe a free air transmission method for the determination of the permittivity of lossy liquids in the frequency range 26–110 GHz and the temperature range -5 to 70 °C. For pure water the method gives permittivity values with a dispersion of less than 3% about the true value. We give new permittivity data for an aqueous NaCl solution and for synthetic sea water in the temperature range -2 to 30 °C. The permittivity data obtained with this technique have been incorporated in a number of numerical weather prediction models and have resulted in more accurate ocean surface emissivity functions for use with microwave and millimetre wave imaging and sounding instruments.