Highly Sensitive Microwave Sensor Based on Planar Resonator Arrangement for Dielectric Material Characterization

This article presents a miniaturized microwave sensor using microstrip line technology for material complex permittivity characterization. The main novelty of the sensor lies in the use of a modified configuration of the asymmetric complementary split ring resonator (ACSRR) by applying the bended-edge strips technique to achieve higher sensitivity and smaller size without occupying extra surface or using nonplanar elements (vias). The bended-edge ANCSRR (BEANCSRR) is implemented on a
$40\times 16\times 0.787$
mm3 substrate and operates at 2.7603 GHz with a quality factor of 115. The sensitivity of the microwave sensor is enhanced by optimizing the dimensions of the resonant area. Various empirical expressions describing the complex permittivity have been implemented with the measured parameters of the proposed sensor. A prototype of the sensor is fabricated and experimentally validated using five dielectric samples with dimensions of
$14\times 10$
mm
$^{{2}}$
, showing excellent agreement between simulation and experimental results. The proposed sensor with a small area of
$0.0046~\lambda _{g}$
demonstrates good performance, with a high resolution of 879 MHz/
$\Delta \varepsilon $
, a sensitivity of 3.46%, and an average error of 4.85%.