Multi-octave microwave absorption via conformal metamaterial absorber with optical transparency

We present the analysis and design of a multi-octave broadband microwave absorber with simultaneous high optical transparency. Assisted by the semi-analytical method, the proposed metamaterial absorber, composed of transparent dielectric substrates and patterned indium-tin-oxide, can achieve an excellent electromagnetic wave absorption in a wide frequency band from 6.21 GHz to 19.31 GHz within a total thickness of only about 0.075 lambda. The experiment results are in agreement with full-wave simulations, demonstrating high-efficient and broadband absorption in a wide angular range from 0 degrees to 45 degrees for all polarizations. In addition, by substituting the middle layers with flexible dielectric layer, we successfully design a flexible metamaterial absorber for conformal applications. The performance of conformal absorber is also verified by simulation and experiment, both of which validate an excellent backward scattering suppression for cylinder object with wavelength-comparable radius. With advantages of excellent absorption, polarization-insensitivity, thin-thickness and especially high transmittance and flexibility, the proposed absorber may have potential uses in many real-world applications.