Slow Microwave Sensor Based on Engineered −1/ x -Like Function Transmission for Improved Sensitivity.

A novel sensing method that uses the separate design of a sensitivity enhancer and sensing zone is reported. Unlike most resonance-based sensors, the flexible design of a sensing zone is beneficial to the increment of effective material-under-test volume. A novel technique to enhance sensitivity is proposed by engineering the −1/ $x$ -like function microwave transmission to slow the energy-flow velocity. The measured large group delay is up to $\sim 16~\mu \text{s}$ at 2.967 GHz. A lumped model is built to study the condition of the engineered transmission. Compared with a regular coplanar waveguide sensor, the sensitivity is improved up to ~227 times when it is connected to the slow microwave circuit. [ABSTRACT FROM AUTHOR]