RCS Reduction of Plasma-Reconfigurable Coding Metasurface Composite Structures

This article investigates the design and optimization of a reconfigurable coding metasurface under plasma conditions, revealing its operational mechanisms in a plasma-coated environment. First, a reconfigurable coding metasurface coated by a uniform plasma is studied. Simulation results show that this uniform plasma–metasurface composite structure achieves a radar cross section (RCS) reduction of more than 10 dB across 6–18.6 GHz, corresponding to a relative bandwidth of 102.4%. This design effectively combines the stealth advantages of plasma in the lower frequency range and the metasurface in higher frequencies, outperforming a standalone reconfigurable coding metasurface, which only operates from 12.2 to 18 GHz. Furthermore, by transitioning from uniform plasma to a nonuniform plasma, the nonuniform plasma–metasurface composite structure is investigated. This composite structure attains over 10 dB RCS reduction (RCSR) across an even wider band of 5.4–18.6 GHz, representing a 110% relative bandwidth—a twofold increase compared to the single reconfigurable coding metasurface. Moreover, under oblique incidence at 60°, the nonuniform plasma–metasurface composite structure maintains over 10 dB RCSR from 7.2 to 17.1 GHz, achieving a 5.6-fold relative bandwidth enhancement relative to the single reconfigurable coding metasurface under the same oblique incidence. The plasma component compensates for the limited RCSR bandwidth of the coding metasurface under large incident angles, offering a new strategy for broadband RCSR at oblique incidences. Finally, a prototype of the reconfigurable coding metasurface was fabricated and tested in a high-temperature plasma environment, verifying the correctness of our design method. This work demonstrates the promising potential of plasma–metasurface composites for stealth applications in plasma-coated environments.