An ultra-broadband low profile modified chessboard metasurface with improved backscattering reduction

• Published in: Optics communications 2025-01, Vol.574, p.131213, Article 131213
• Main Authors: Rangula, Madhusudhan Goud, Paul, Princy, Majumder, Basudev, Kandasamy, Krishnamoorthy
• Format: Article
• Language: English
• Subjects: Backscattering; Bistatic; Cross polarization conversion; Metasurface; Monostatic; Oblique incidences; RCS reduction
• ISSN: 0030-4018
• DOI: 10.1016/j.optcom.2024.131213

Building upon the concepts of polarization conversion and the mechanism of destructive interference, a single-layered ultra-broadband metasurface for radar cross-section (RCS) or backscattering reduction is proposed in this work. A diffusion-assisted checkerboard metasurface with re-tailored unit cells at the center leads to a significant improvement in the stealth characteristics. For this, a low profile and less complex unit cell is proposed, comprising a long metallic strip along the diagonal and two thin horizontal stubs at the edges. This unique arrangement exhibits more than 90% polarization conversion efficiency from 13.2 to 38.2 GHz. Modifying the geometry of central elements in a conventional checkerboard metasurface achieves a minimum of 15 dB RCS reduction from 10 to 38 GHz. Also, as we ascend the frequency spectrum, the beams are scattered in unintended directions with reduced signal strength. Notably, there is no beam in the boresight direction, as opposed to the conventional chessboard configurations. For off-normal incidences, the metasurface exhibits good angular stability, and a minimum of 10 dB backscattering reduction is maintained up to an incidence angle variation of 60°. The final optimized fabricated prototype exhibits measurement results that agree with the simulation results for normal and wide-angle incidences. ➢This work proposes a single-layered ultra-broadband metasurface for radar cross-section (RCS) or backscattering reduction based on polarization conversion and the mechanism of destructive interference.➢To realize this, a low-profile reflective-type unit cell with efficient cross-polarization conversion capabilities is synthesized, which comprises of a long diagonal conductive strip with attached stubs at the edges on the top layer of the substrate and a metallic ground plane at the bottom. More than 90% cross-polarization conversion efficiency is obtained over the entire broad bandwidth.➢Conventional chessboard metasurfaces of different configurations (formulated based on unit cell arrangement in sub-arrays) are labeled as MS#1, MS#2, MS#3, MS#4, MS#5 are studied, and their monostatic and bistatic patterns are evaluated.➢It is observed that increasing the number of unit cells grouped in an array can improve the RCS performance only to a limited extent. Alternatively, a diffusion-assisted checkerboard metasurface with novel rearrangement of unit cells at the center leads to a significant improvement in the stealth character