Simultaneous measurement of thickness and permittivity using microwave resonator‐based planar sensor

Abstract

This article presents a microwave sensor for dielectric characterization and thickness measurement of solid materials. The proposed sensor incorporates an interdigital capacitor (IDC) and a split-ring resonator to create an intense electric field, allowing it to efficiently interact with a sensing material. IDC parameters such as width and gap of the finger and length and gap of the electrode are optimized to enhance the material characterization sensitivity. The microwave resonant sensor structure is designed to operate at 1.8 GHz, making it applicable to measure permittivity and thickness of solid materials. The proximity of the material to be sensed influences the field distribution of the developed sensor, which, in turn, enables the simultaneous measurement of permittivity and thickness based on variations in a resonant frequency. Experimental results reveal that the highest sensitivity value reaches 113.4 MHz/mm and 47.6 MHz/Δε r for permittivity of the solids, when the thickness is between 0 and 1 mm. Furthermore, the developed sensor demonstrates a high accuracy (99.6%) and adequate accuracy (87.6%) for both real and imaginary permittivity, respectively. The developed microwave resonant sensor also shows excellent resolution for permittivity (0.04716) and thickness (0.1314), validating its high-performance for measuring permittivity and thickness for various solids.

Design and test of an inkjet-printed microwave interdigital capacitor on flexible Kapton substrate

“…The proposed IDC is meant to be used for sensing applications and, in this case, spurious resonances are desirable since they may be exploited as trackers [31]. In the literature, IDCs and, in general, planar resonators have been employed for sensing purposes and they exhibited good performance when used in the frequency range between 1 GHz and 5 GHz [32][33][34][35][36]. For this reason, the proposed IDC is designed to operate on this frequency band.…”

Sensing Performance Enhancement Based on High-Frequency Polarization of Materials

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Real‐Time and High‐Accuracy Microwave Frequency Identification Based on Ultra‐Wideband Optical Chirp Chain Transient SBS Effect

“…Real-time and high-accuracy measurement can provide the time-frequency characteristic of microwave signals in a realtime dynamic fashion, while enabling clear analysis of the generating source. In recent years, such measurements have quickly attracted interest for applications in astronomy, [1][2][3] communications, [4] materials, [5][6][7][8] medicine, and healthcare, [9][10][11][12][13][14][15] and devices. [16] For these applications, electronic solutions are the most straightforward and widely implemented microwave measurements today.…”