Differential Microwave Sensor Based on Spiral Resonators Operating in the Sub-6 GHz Band
DOI:
https://doi.org/10.18607/ES20261521762Keywords:
Dielectric Constant, Differential Measurement, Microwave, Sensing, Spiral ResonatorAbstract
The objective of this work is to present the design and computational simulation validation of a differential microwave sensor for the characterization of the electrical permittivity (εM) of dielectric materials in the sub-6 GHz band. The proposed topology is based on the Modified Two-Turn Spiral Resonator (M2TR-SR). The differential technique employs two coupled resonators, mitigating errors caused by uncontrolled environmental interferences and increasing the analytical reliability of the measurements. The device was designed in Ansys HFSS software to present initial resonance frequencies near 4 GHz and 5 GHz. The structure’s performance was evaluated by subjecting it to materials under test (MUT) with permittivities ranging from 1 to 5, aiming to demonstrate the device’s capability as a high-resolution sensor. The parametric mapping revealed an absolute performance peak at εM = 2.0, recording a Frequency Detection Resolution (FDR) of 0.157 GHz (157 MHz) and a sensitivity (Sp) of 13.62%. Even at the upper tested limit (εM = 5.0), the sensor showed continuous robustness, sustaining an FDR of 0.090 GHz and a sensitivity of 7.81%. Polynomial regressions proved the system’s high mathematical predictability (R2 = 0.9865). Thus, the proposed device constitutes a promising platform for analytical and industrial nondestructive sensing applications.
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Copyright (c) 2026 Paulo Ricardo Pazetto Barbosa, Prof. Dr. Guilherme Lopes de Figueiredo Brandão, Prof. Dr. Pedro Luiz Lima Bertarini (Autor)

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