Fig. 3: Spectral and electric characteristics of fabricated metamaterials.
From: Microwave-transparent metallic metamaterials for autonomous driving safety
a Visible camera image of a Cu metamaterial with a metal filling ratio of 71.3 % fabricated on a glass cover. Scale bar, 2 cm. b Measured (solid lines) and simulated (dashed lines) transmission (S21) spectra (75–110 GHz) of four (Meta I–IV) fabricated metamaterial samples. The key parameter values of each metamaterial design are listed in Supplementary Table 3. (Insets) Visible camera image of each sample. Scale bar, 2 mm. c Simulated phase delay values when an incident microwave signal is reflected from one end of the glass substrate including the metamaterials (Meta I–IV). The grey dashed line represents phase delay values calculated from the analytical standing wave condition. The coloured dashed lines represent transmission peak frequencies from the measured S21 spectra of the four fabricated metamaterial samples. (Inset) Electric field profiles of Meta I at 82.5 (on resonance) and 110 GHz (off-resonance). d Measured S21 phase values the four (Meta I–IV) metamaterial designs. e Measured sheet resistance values of the fabricated samples (Meta I–IV and Mesh I–III). (Inset) Measured transmission spectra of reference samples based on two-dimensional mesh arrays with discrete metal filling ratios (5 %, 30 % and 70 % for Mesh I–III, respectively). For comparison, an uncoated glass substrate is plotted as dashed line.
