Note: Coaxial apparatus to measure the permittivities of chemical solutions at microwave frequencies.

Traditional permittivity measurements in microwave chemistry have some limitations on bandwidth and probe erosion. To resolve these problems, in this note, an apparatus that realizes a real-time wide-band non-contact measurement is proposed. Scattering parameters are obtained from measurements made using the proposed coaxial apparatus. These parameters are used to reconstruct the permittivities of several solutions using artificial neural networks. The maximum deviations in measured permittivity at 2.45 and 5.8 GHz are within 5% of results from the literature, showing the obvious advantages of coaxial apparatus with artificial neural network reconstruction over conventional apparatus.