Caracterizarea materialelor solide și lichide pe bază de senzori microstrip de sensibilitate mare / Characterizing both solid and liquid materials based on high sensitivity microstrip sensors

Abstract of doctoral thesis in English. After the review described in Chapter one regarding various studies and examples of implementation of planar microwave sensors in material characterization, Chapter 2 mainly focuses on the most important and complex permittivity extraction techniques on microwave sensor-based planar resonators to extract properties of materials. In Chapter 3, a new approach is proposed to extract the electrical parameters of the transmission line equivalent circuit of complementary split-ring resonators (CSRRs) and a good agreement between the simulation results and those extracted through the proposed approach is obtained. In Chapter 4, a new model of a planar microwave sensor constructed on a CSRR coupled with an air hole in the structural substrate is presented to accurately measure the permittivity of materials. It was found that the proposed sensor provides three times greater sensitivity than conventional planar sensors. In Chapter 5, a sensor using modified Split Ring Resonators (SRRs) is designed, simulated, fabricated and used for measurements of the complex permittivity. Measurements of various samples, such as clear glass, acrylic glass, plexiglass, and Teflon, confirm that the modified SRR sensor is easy to implement and gives accurate results for all cases, with measurement errors of less than 4.5%. In Chapter 6, a highly accurate microstrip differential sensor was designed, manufactured, and tested for the complex permittivity characterization as well as the percentage of water content of urine samples. Various samples of urine water content in percentages were tested, such as 0% urine (100% water), 20% urine, 33% urine, 50% urine, 66% urine and 100% urine. The sensitivity of the sensor is about 3%.