Fractal Metamaterial Surfaces for UHF Sensing Applications.

A dual-band fractal metamaterial absorber is proposed as a promising alternative for sensing applications. A preliminary prototype, useful to validate the proposed configuration, is designed to operate in the Ultra-High Frequency (UHF) range. The inherent miniaturization skills of fractal geometries are effectively exploited to design and fabricate multiband/broadband absorbers with a small lattice size (≤λ ₀ /2 at the smaller operating frequency f ₀ ) and a very thin profile (≤λ ₀ /100). Two pairs of Minkowski fractal patches, alternately arranged in four different quadrants and properly sized to achieve two distinct absorption peaks, are assumed for the absorber-sensor configuration. Good sensing performance in terms of sensitivity and quality factor (Q) is achieved in the framework of dielectric material diagnostics. Very high absorption rates (>99%) and a quite good angular stability are demonstrated both numerically as well as through experimental validations, thus proving the applicability of the proposed absorber sensor in low-frequency sensing applications.