Design of a Groundless Metamaterial Absorber Based Sensor Integrated into X-Band Waveguide

This work presents two different novel groundless absorber based sensor design to be integrated in a single mode waveguide. This metamaterial absorber is used in high resolution measurements of variations in the permittivity of the dielectric material where variations in the dielectric constant can be detected by considering the shift in the resonant frequency. The sensor is analyzed in terms of transmission, reflection and absorbance parameters. The first design configuration proposed gives transmission and reflection below -15 dB at the design frequency 11.5 GHz which concludes an absorption of 97%. As for the second proposed groundless configuration, it gives transmission and reflection below -30 dB 9.75 GHz which concludes an absorption of 99.7%. The reflection spectra for different values of superstrate permittivity for both configurations is reported and a comparison was conducted between both configurations and previously reported designs to summarize the efficiency of the proposed design structures.