Reconfigurable microwave SIW sensor based on PBG structure for high accuracy permittivity characterization of industrial liquids

•The tunable microwave sensor for permittivity determination of industrial liquids have been considered.•The Substrate Integrate Waveguide (SIW) is used for making the cavity for improve sensing.•The Photonic Band Gap method is utilized for improve the electric field in the hot spots.•The cavity perturbation technique in order to calculate the permittivity is employed. In this paper, we present a novel tunable microwave sensor for permittivity determination of industrial liquids. The proposed sensor is cavity based which is developed on a Substrate Integrated Waveguide (SIW). To enhance the characterization accuracy, the reconfigurable sensor is equipped with a Photonic Band Gap method and variable capacitors. Moreover, we employ the cavity perturbation technique in order to calculate the permittivity. In the characterization process, we obtain the permittivity of an unknown material by considering a resonant frequency shift. In fact, a capacitance is the main parameter for controlling the sensor resonance. We herein change this capacitance via reconfigurable SIW cavity and applying different materials. The proposed tunable architecture lets us study the material characteristic in the wider frequency range. The structure is designed in 5–6 GHz in order to determine the electromagnetic behavior of a brand new and used transformer oil samples. The results present a highly accurate permittivity of these oil samples. Hence, the proposed method and setup is not only suitable for oil ageing programs, but also applicable for other industrial liquid applications.