Fatemeh Kazemi

Miniaturization of terahertz (THz) absorbers is crucial for advancing compact and efficient electromagnetic (EM) devices. This study investigates the impact of various spoof plasmon topologies T-slot, grating, and L-slot on the miniaturization and performance of THz metamaterial absorbers (MAs). The proposed designs utilize dual-ring and single-ring gold structures on a quartz spacer. Our structures demonstrate up to 15% size reduction while maintaining high absorption rates (96%–98%). The L-slot topology exhibits optimal performance with absorption peaks at 0.758 and 0.984 THz (dual ring) and 1.00 THz (single ring), compared to the conventional design’s 0.77-/1.15- and 1.14-THz resonances, respectively. Comprehensive analyses reveal that spoof structures significantly alter phase response, modify group delay characteristics, and enhance electric field distribution uniformity across the resonator surface. The coupled mode theory (CMT) model accurately predicts these behaviors with parameters extracted from simulation results.

Microwave imaging is an emerging tool for medical diagnostics, potentially offering unique advantages such as the capability of providing quantitative images of the inspected tissues. However, this involves solving a challenging nonlinear and ill-posed electromagnetic inverse scattering problem. In this paper, design, fabrication, and characterization of a near-field microwave scanning probe for sub-surface imaging is presented. The focus is on an application of microwave biomaterials reflectometry imaging. Operating frequency is fixed at 18.5GHz. In order to obtain a 2D image, a network analyzer system monitors changes in the amplitude of the reflection coefficient (S11), quality factor (ΔQ), and resonant frequency (Δf). Results and findings which are presented here, are expected to have strong implications in a wide range of subsurface detection challenges including detection of biological anomalies in human tissue, and etc.