Development of a microstrip antenna for dielectric constant measurement in liquid insulations

Most constraints applied to liquid insulations induce a certain variation of their dielectric properties, including their dielectric constant (permittivity). This work will be oriented towards the detection of the variations of this property in order to determine the state of oil. The oil deterioration in power transformers is associated to different particle formation as carbon, dissolved gases and furane derivatives generation that will cause the variation of the relative permittivity of this oil. For that purpose, a sensor enabling to detect the permittivity variations will be developed. It consists on an antenna in microstrip technology (patch antenna) that operates in microwave domain and whose characteristics are influenced by the change of parameters of the medium where it is inserted.