Complex permittivity measurement using metamaterial split ring resonators

Abstract

A direct and efficient method for determining the complex permittivity of materials at microwave frequencies using a Split Ring Resonator (SRR) metamaterial structure is presented. A single SRR unit fabricated on a substrate arranged between transmitting and receiving probes acts as a test probe. Dielectric samples having at least one flat surface of area greater than or equal to the area of SRR structure are used as test samples. The relative permittivity and the loss tangent of the dielectric are evaluated from the resonant frequency shift and the bandwidth of the SRR resonator, by placing the sample over it. The LC resonance of the SRR test probe is theoretically related to the permittivity by considering its equivalent circuit in terms of the dielectric filled capacitances formed on the upper and lower surfaces of the SRR. The permittivity measurements are performed using test probes of different resonant frequencies, and the results are compared with the values obtained by the cavity perturbation method.

Surface Crack Detection in Pipelines Using CSRR Microwave Based Sensor

“…The resonant frequencies were observed to shift toward higher frequencies when the sensor was positioned over the holes, and the same trend occurred for the Q-factor. This shift agrees with the results predicted by numerical and simulation methods in other works [39,40]. Figs.…”

Symmetric coplanar waveguide sensor loaded with interdigital capacitor for permittivity characterization

“…The complex permittivity values (𝜀 𝑟 ′ and tanδ) of MUT are extracted by feeding the experiment data into the BP neural network algorithm, and the results are presented in Table . It can be noticed that the obtained permittivity data consistent with the referred values available in the literature . The maximum error in the real part of the dielectric property (ε r ′) of the selected MUT is between 0.31% and 3.42%, while the maximum errors in loss tangent part (tanδ) are between 0.63% and 3.39%, respectively.…”

Improved approach using symmetric microstrip sensor for accurate measurement of complex permittivity

“…In the former, the resonator is mainly composed of waveguides but usually suffer in large size and cumbersome experimental preparation process. In the later, the resonant techniques based on the planar microstrip line are preferable because of their low cost, lightweight, and ease in fabrication, and it has been the subject of an intensive research activity in the last years …”

“…For microwave sensors loaded with planar resonators, the sensing part of a microwave material characterization system can be constructed using either a single resonator, such as split‐ring resonator (SRR) . complimentary SRR (CSRR), or interdigital capacitor (IDC) .…”

“…In the later, the resonant techniques based on the planar microstrip line are preferable because of their low cost, lightweight, and ease in fabrication, and it has been the subject of an intensive research activity in the last years. [17][18][19][20][21][22][23][24][25][26][27][28][29] For microwave sensors loaded with planar resonators, the sensing part of a microwave material characterization system can be constructed using either a single resonator, such as split-ring resonator (SRR). [18][19][20][21] complimentary SRR (CSRR), [22][23][24][25] or interdigital capacitor (IDC).…”