Ultrawideband RCS Reduction Metasurface Based on Hybrid Mechanism of Absorption and Phase Cancellation

In this article, an ultrawideband radar scattering cross-sectional (RCS) reduction metasurface is proposed combining with absorption and phase cancellation mechanisms. A two-lossy-layer absorber is designed first, which is responsible for low-frequency RCS reduction from 1.3 to 13 GHz (163.6%). The equivalent circuit of the proposed absorber is extracted, proving that the wideband characteristic is due to the occurrence of multiple resonant points. To further improve the RCS reduction bandwidth, the absorber unit cells are arranged with three different heights. The proposed metasurface consists of 3 $\times $ 3 lattice and each lattice has $5\times $ 5 absorber unit cells. The reflection phase cancellation can be achieved owing to the wave path difference by introducing a certain height difference among subregions. Resultantly, high-frequency RCS reduction from 13 to 40 GHz can be realized since the backward scattering can be canceled effectively. Finally, an extraordinary ultrawideband RCS reduction from 1.5 to 40 GHz (185.5%) can be acquired successfully. A prototype with the thickness of 0.104 $\lambda _{L}$ (the wavelength of the lowest working frequency) is fabricated and measured for demonstration. The measured results prove that the proposed design has numerous advantages including minimization, ultrawideband RCS reduction, wide angle stability, and polarization insensitivity.