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This paper presents an active microwave sensor for the characterization of dielectric materials. The sensor is consisted of a microstrip complementary split-ring resonator (MCSRR) structure and an active feedback loop. The loop uses an amplifier to generate negative resistance to compensate the resonator’s loss and increase the loaded quality factor. The developed sensor possesses the advantages of high quality factor, ultra-small electrical size, and high sensitivity. A prototype of the sensor is fabricated and measured for validation.

This paper presents a differential microwave microfluidic sensor based on the microstrip complementary split-ring resonator (MCSRR) structure for liquid characterization. At the resonance, the electric field concentrates along the slot, where the microfluidic channel is located. As the liquid sample is injected, the corresponding reflection coefficient is changed, while the reference response is unaffected. The relative permittivity and loss tangent of the liquid can be extracted from the variations in the resonant frequency and quality factor. A prototype of the proposed sensor is fabricated and measured for functionality validation. The proposed sensor exhibits a high sensitivity of 0.626% on average and is capable of suppressing unwanted environmental influences.

This paper presents two complementary split-ring resonator (CSRR)-based sensors for full characterization of magneto-dielectric materials. The first proposed sensor is designed by loading the microstrip line with a CSRR, while the second one is by loading the microstrip line with two CSRRs. To distinguish the effects of permittivity and permeability on the shift of resonant frequency, the electric and magnetic fields are designed to be located at two separate zones in the CSRR. Two 50Ω resistors are mounted at the ends of the microstrip line to increase the quality factor. In addition, the second sensor can perform measurements of complex permittivity and complex permeability of the magneto-dielectric materials in a single run, thereby making the measurement faster, easier, and in a more cost-effective way. The prototypes of two proposed sensors are fabricated and tested for validation of their functionality. A good agreement can be achieved between the measured data and the reference values from the manufacturers' datasheet, thereby demonstrating the applicability of the proposed sensors for full characterization of the magneto-dielectric materials.

This paper presents an improved complementary split-ring resonator (CSRR)-based sensor for differential measuring permittivity and permeability of magneto-dielectric materials. The sensor has two identical resonator elements, one of which is used as reference and the other is used to characterize magneto-dielectric materials. By combining these two resonator elements together, the sensor can fully characterize the magneto-dielectric materials with the environmental interference suppressed effectively.

学位の種別: 課程博士, 審査委員会委員 : （主査）東京大学教授 岩田 忠久, 東京大学教授 竹村 彰夫, 東京大学准教授 斎藤 継之, 東京大学准教授 榎本 有希子, 京都大学教授 和田 昌久

This letter proposes a microwave planar sensor for the characterization of magnetodielectric materials. The sensor is designed by loading microstrip lines with complementary split-ring resonators (CSRRs). Two patches are connected to the microstrip lines to couple with the CSRRs, and a pair of 50- $\Omega $ resistors are in series with the lines to provide a notch. The designed sensor can extract the permittivity and permeability of the magnetodielectric materials simultaneously. A prototype of the designed sensor is fabricated and measured for validation of characterizing the magnetodielectric materials.

A high-Q sensor based on substrate integrated waveguide (SIW) technology is designed to fully characterize magneto-dielectric materials. By utilizing the negative resistance circuit, the quality factor is further increased to an ultrahigh value of 13,399. By virtue of the improved complementary split ring resonator (CSRR), the complex permittivity, as well as the complex permeability, can be extracted from variations of the resonant frequency and magnitude. A prototype of the designed active SIW-based sensor is fabricated and validated experimentally. A good agreement can be achieved between the measured values and the reference data.