Fig. 1. (a) Structural design drawing of metasurface. (b) Top view of the functional layer structure. (c) Side view of the entire structure and thickness of each layer. (d) Top view of the “0” coding unit. (e) Top view of the “1” coding unit.

Fig. 2. (a) Phase and amplitude response of the “0” and “1” units. (b) Energy ratio of the designed metasurface within 4–14 GHz for the absorption, scattering, and reflection of the incident EM wave. (c) Average energy ratio of the designed metasurface to the absorption, scattering, and reflection of incident EM waves in the 4.5–10.3 GHz band. (d) Top and side views of the surface current distribution of the metasurface at 6 GHz.

Fig. 3. (a)–(c) Far-field scattering patterns of the designed metasurface and metal at 6 GHz, 8 GHz, and 10 GHz. (d) Simulation curve of metasurface backscattering reduced reflection characteristics at 2–18 GHz.

Fig. 4. (a) Far-field scattering results at 11.5 GHz for the metasurface with reduced ITO patch side length b. (b) Far-field scattering results at 12 GHz for the metasurface with both reduced ITO patch side length b and increased inner ring side length t.

Fig. 5. (a) Simulation environment and sample images. (b) Comparison between the measured reflection curve and the simulated reflection curve. (c) Far-field reflection test results of the samples at 6, 8, and 10 GHz at 45°.

Fig. 6. (a) Results of sample emissivity measurement by IR emissivity tester. (b) FTIR spectrograph measurement of sample emissivity at 3–14 μm. (c) IR thermal imager. (d) IR thermal images taken after the sample was heated at 20°C, 70°C, 120°C, and 170°C for 10 min.