Abstract
In this Letter, an all metallic sensor based on ε-near-zero (ENZ) metamaterials is studied both numerically and experimentally when working at microwave frequencies. To emulate an ENZ medium, a sensor is made by using a narrow hollow rectangular waveguide, working near the cutoff frequency of its fundamental TE10 mode. The performance of the sensor is systematically evaluated by placing subwavelength dielectric analytes (with different sizes and relative permittivities) within the ENZ waveguide and moving them along the propagation and transversal axes. It is experimentally demonstrated how this ENZ sensor is able to detect deeply subwavelength dielectric bodies of sizes up to 0.04λ and height 5 × 10−3 λ with high sensitivities (and the figure of merit) up to 0.05 1/RIU (∼0.6 GHz−1) and 0.6 1/RIU when considering the sensor working as a frequency- or amplitude-shift-based device, respectively.
Highlights
Matter interactions given their exotic features of near-zero propagation constant and almost infinite effective wavelength of the wave traveling through them
It was demonstrated that such artificial media can be emulated by exploiting the intrinsic structural dispersion of rectangular waveguides working near the cutoff frequency of their fundamental mode TE10.18 ENZ metamaterials have rapidly evolved in the recent years demonstrating their applicability in diverse scenarios such as in power splitters,19 antennas and lenses,7,20,21 and dielectric sensors,22,23 among others
We demonstrated both theoretically and numerically how narrow hollow rectangular waveguides emulating ENZ metamaterials can be used as sensors for small dielectric particles with subwavelength sizes,25 complementing previous sensor designs26,27 based on cutoff waveguides that did not consider ENZ operation
Summary
Matter interactions given their exotic features of near-zero propagation constant and almost infinite effective wavelength of the wave traveling through them.16,17. The performance of the sensor is systematically evaluated by placing subwavelength dielectric analytes (with different sizes and relative permittivities) within the ENZ waveguide and moving them along the propagation and transversal axes.
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