Non-Destructive Testing Using Transmission Line-Based Microwave Sensors

In this study, some types of antennas and metamaterial structures have been designed and produced with the aim of determining and detecting ionized chlorine of sea sand in concrete. The first structure has a Loop-like resonator with the sample, the second structure has a Bowtie-shaped resonator with the sample and the third structure has double loop resonators on both sides of concrete samples also non-destructive method is applied for all structures. Different samples of concrete are produced with different proportions of ionized sea sand. Electrical properties of concrete samples for all structures are investigated in the frequency range of 1-9 GHz. The structures are designed in the CST Microwave Studio program. Also, the simulation study of the designed structures shows that the most important resonance frequency changes, considering the dielectric constant of concrete samples, for the Loop-like structure occur in the 1-8 GHz, Bowtie-shaped structure in 1-4 GHz and double Loop structure in 1-9 GHz of frequency band. The important point in this study is the changes of the waveform at the resonance frequency. The output waveform (reflection coefficient S11/ transmission coefficient S12) should change in linear form by considering the dielectric coefficient. We have used copper for the resonators and also the material with ℇ value of 3 as the substrate layers of the structures. We have simulated three types of designed structures with CST Microwave Software and then achieve the results and evaluate them. Both numerical and experimental tests have given approximately same results and are in good agreement with each other. These proposed structures can be used in many applications where it is necessary to determine the rate of ionized sea sand in cement-based composites such as concrete.