WATER - A DIELECTRIC REFERENCE

Our ultimate objective is to help establish an international consensus for a dielectric reference standard with the permittivity of water in the frequency range 0-1000 GHz and the temperature range 0 degrees-10 0 degrees C. The first step, which is exposed in this article, is a cr itical bibliographic analysis and a compilation of the published permi ttivity data for water. Using this compilation we have developed a dyn amic interpolation scheme which gives the ''best'' value for the permi ttivity of water, at a given frequency and temperature, together with an estimate of the uncertainty in the calculated value. As new experim ental measurements are introduced into the data base the interpolation scheme is automatically refined. The second step depends upon the col laboration of our readers. We welcome constructive criticism new permi ttivity data etc. It is only by such a co-operation that experimental measurements and uncertainties can be evaluated and an international s tandard established. It is our intention to make the data base and all the associated computer programmes available, free of charge, upon re quest.