Metamaterial absorber-based sensor embedded into X-band waveguide

A novel metamaterial sensor, integrated with an X-band waveguide, is proposed for high-resolution measurements of variations in the dielectric constant and/or the thickness of a superstrate layer that covers a pair of absorber unit cells. Variations in superstrate parameters are potentially caused by physical, chemical or biological factors, and can be detected by measuring the corresponding shifts in the resonance frequency of the metamaterial sensor. It is estimated by simulation results that resolution levels as good as 1.1 μm change in thickness or 0.023 absolute change in relative permittivity of the sensing layer are feasible for a 10 MHz measurable shift in resonance frequency. Simulation results obtained for the fabricated prototype are verified experimentally with good agreement.