A high-Q annular ring antenna as a microwave near-field material sensor

Abstract

In the past few years, many microwave near-field sensors based on metamaterial unit cells have been reported having a low-quality factor. In this paper, we present an approach to design a sensor with very high localized fields and quality factor. The sensor is based on a loaded annular ring antenna operating at the microwave regime. The sensor is designed and simulated using a full-wave simulation tool. The results shows that a quality factor of 430.5 at −10 dB can be achieved with a fractional bandwidth of 0.0023. A high quality factor gives indication that the sensor can be sensitive to changes in the real and imaginary part of the dielectric constant of the material under test. Our design concept was validated using numerical simulation by detecting small variations in the real part of a dielectric slab.