Employing higher order modes in a broadband SIW sensor for permittivity measurement of medium loss materials

Abstract

In this paper, a novel SIW microwave sensor is designed to accurately determine the broadband complex permittivity of medium loss and dispersive liquids using a number of higher order modes in 11–20 GHz. To achieve a higher accuracy in characterization, the sensor is equipped with some methods such as Photonic Band Gap method, slow-wave via, and a new feedline, which enhances the quality factor for the higher order TE1,0,n modes. The operating principle of this sensor is based on the cavity perturbation technique, in which the resonant properties of the cavity are utilized to extract the dielectric properties of liquid under test. To provide a method to decrease the LUT consumption, a winding microfluidic channel is designed and embedded in the cavity. The channel increases the interaction between the induced electric field and the LUT. The accuracy of different perturbation technique for determination of permittivity is compared with each other.

Material Characterization Innovations in Microwave Measurement Laboratory of Amirkabir University of Technology

“…An approximate perturbational analysis is carried on the structure to relate the resonant frequency of the perturbed system to that of unperturbed one. The formulation is available in the literature for elementary structures [25]. For a custom design, one can extract the necessary equations.…”

“…where 𝐹 is the filling factor and depends on size and location of the sample in the cavity. The equations for this parameter are available in the literature [25][26]. 𝜔 𝑟 and 𝑄 𝑇 the resonant angular frequency and the overall quality factor, respectively.…”

“…In the recent researches, [22=25], some of these limitations have been relaxed, which in turn have enhanced the sensitivity. Some researchers hire machine learning approaches for identifying the materials based on collected data [25][26]. Artificial neural networks are suitable for reconstructing complex permittivity according to the measured values.…”