A system has been developed for direct traceable dielectric measurements on liquids at high pressures and temperatures. The system consists of a coaxial reflectometric sensor terminated by a metallic cylindrical cell to contain the liquid. It has been designed for measurements on supercritical liquids, but as a first step measurements on dielectric reference liquids were performed. This paper reports on a full evaluation of the system up to 2.5 GHz using methanol, ethanol and n-propanol at pressures up to 9 MPa and temperatures up to 273 °C. A comprehensive approach to the evaluation of uncertainties using Monte Carlo modelling is used.

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Smart windows that regulate the transmission of visible light are well known, but with the continuing interest in modifying the radar signature of military hardware, there is a need also for smart microwave windows and surfaces. The paper reviews progress on the fabrication and characterization of poly(aniline)-silver-polymer electrolyte composite materials. Discs and films of this material have been characterized over the frequency range 0.5-18 GHz. The materials demonstrate a rapid and reversible change in their microwave reflectivity when a small dc potential is applied across them. The best samples have exhibited a reflectivity change in excess of 20 dB in a coaxial line test set. Cyclic voltammetry studies of these composite materials are discussed in the light of a poly(aniline)|polymer electrolyte|silver single-cell model. The effect of the poly(aniline) counter ion, the polymer electrolyte and the application of a bias potential on the dc and microwave results is discussed. Geometries of smart surfaces that might utilize these materials are then proposed and their characteristics are evaluated.

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