Broadband Complex Permittivity Sensor for Liquids

This work presents the design, construction and electrical characterization of a broadband permittivity sensor for liquids, apt for use in industrial environments. It is made of plated steel, bronze and aluminum, which guarantees compatibility with many liquids. The characterization of the sensor is carried out in the frequency range between 1 MHz and 200 MHz, for liquids with permittivities ranging from 2 to 80. The results are satisfactory in terms of sensor construction, being easy to build and to clean, robust, low-cost, and versatile. From the characterization, it is verified that its electrical losses are very low, and that its first self-resonance frequency is well above the frequency operating range.