Estimation of Water Conductivity Using a Coaxial Cell under Temperature Change

The effects of temperature and humidity have a significant impact on the performance of radio electronic systems. In harsh operating conditions because of constant temperature changes in radio electronic equipment, condensation may form and affect its normal functioning. Depending on temperature and aggregate state, water has different electrical characteristics. In this paper, the influence of temperature on electrical conductivity of water was estimated using a coaxial cell with a water-filled container placed inside. The temperature of the cell varied from minus 50 to $100^{\circ} \mathrm{C}$ and the volumes of water in the container were changed to measure the frequency dependences of S parameters of water in the range up to 12 GHz. The effect of temperature on the frequency dependence of S-parameters was compared. The frequency dependences of electrical conductivity for the water volumes of 5 and 10 ml were calculated at different temperatures. It was revealed that temperature has a different effect on the change of water electrical conductivity depending on the volume. It is shown that when water is exposed to positive temperatures, its conductivity changes within the range of 1.8 and $4.2 \mathrm{Sm} / \mathrm{m}$, and when it is exposed to negative temperatures, the conductivity changes from 0.5 to $1.8 \mathrm{Sm} / \mathrm{m}$ for the 5 and 10 ml water volumes, respectively.