Measurement of Complex Permittivity using Planar Resonator sensor

A Microstrip loop resonator sensor designed to determine the dielectric constant of a liquid is proposed. The resonator sensor designed for 1GHZ for different structure of loop is described. The sensor is implemented using planar microstrip technology. A dielectric material is placed above microstrip ring resonator. As a consequence the near field of the resonator interacts with the material under test (MUT) and the electrical characteristics of the resonator change in relation to the permittivity of the material. The proposed models are extremely compact and experimentally verified by the measurements for liquid sample. A vector network analyzer is used to measure the shift in resonant frequency and the corresponding amplitude of the transmission parameter for the fundamental mode. The design procedure is described and experimental results are reported validating the sensor performance.