A High-Sensitivity Wilkinson Power Divider Sensor for Detecting Dielectric Properties in Edible Oils
摘要
This article presents the development and application of a high-frequency microstrip sensor based on a novel Wilkinson Power Divider (WPD) for the dielectric characterization of edible oils. The innovative design omits the conventional isolation resistance, instead utilizing the dielectric properties of edible oils to influence the isolation parameter (S32) between the output ports. By observing the changes in S32, which is sensitive to the dielectric properties, the dielectric constant of the oils can be accurately determined. The proposed WPD structure includes three coupled lines, resonators, and shorted stubs to improve signal isolation and sensitivity. The permittivity measurement is conducted by placing a 0.01 ml oil sample between the two output ports of the WPD, where its dielectric constant directly alters the impedance and isolation characteristics. The sensor is calibrated using materials with known permittivity to create a reference curve, allowing precise determination of the dielectric constant of unknown samples. The presented structure’s operating frequency is 1.7 GHz, and its dimensions are only 10.3 mm × 10.5 mm. The sensor achieved a high sensitivity of 887 MHz per unit change in dielectric constant, demonstrating its effectiveness in detecting small changes in the dielectric properties of the materials. This study also highlights the importance of calibration and confirms the sensor’s reliability, with repeated measurements showing high consistency. With its enhanced sensitivity and non-invasive measurement capabilities, this novel sensor design offers a valuable tool for the food industry, ensuring the quality and authenticity of edible oils through precise dielectric characterization.