volume | PIER Journals

Abstract

This work introduces an innovative fractal microstrip sensor, shaped like a Māra cross enclosed within a square, designed and fabricated on a Rogers RT5880 substrate for high-precision detection and characterization of edible oils. The proposed resonant shape enhances electric-field concentration and improves the interaction between the material under test and the electromagnetic field, resulting in improved sensitivity and resonant response. The sensor operates at a frequency of approximately 4 GHz within the S-band, with an area of 50 × 50 mm², making it suitable for portable and low-cost applications. The results demonstrated clear frequency shifts for various oil types, including coconut oil, olive oil, sunflower oil, and sesame oil. A mathematical model was also developed to extract the complex electrical permittivity with a high coefficient of determination of 0.99, showing excellent agreement between the experimental and theoretical results. The fractal sensor exhibits a remarkable normalized sensitivity of 0.86% and 3.56% per unit dielectric variation and error of 0.03% and 0.13%, with frequency shifts of 163 MHz and 103 MHz for water and ethanol detection, respectively. Maximum sensitivities reached 15.23% for olive oil and 11.32% for sunflower oil, surpassing many previously published studies.

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Dr. Ahmed A. Al-Mudhafar

Dr. Sarah J. Ghazi