Dartboard Metasurface for RCS Reduction and OAM Wave Generation

The metasurfaces (MSs) of dartboard layout for radar cross-section (RCS) reduction and for both RCS reduction (RCSR) and hollow orbital angular momentum (OAM) wave generation are designed and constructed in this article. First, a polarization conversion unit cell and its rotated structure are applied to construct the 1-bit phase dartboard MSs (DMSs) for RCSR. The 1-bit phase DMSs achieve more than 10 dB monostatic RCSR at 4.1–17 GHz (122.3%) under the normal incidence of both linearly polarized (LP) and circularly polarized (CP) waves. Then, the Pancharatnam-Berry (P-B) phase generated by rotating the entire periodic polarization conversion unit cell array, which can eliminate the impact of coupling-related distortion in the unit cell array, is applied to construct the circular phased DMSs, which the phases of lattices are varied along the circular ring, for both RCSR and OAM wave generation under the far-field incident wave. The circular phased DMSs can achieve more than 10 dB monostatic RCSR at 4–17.1 GHz (124.2%) under the normal incidence of both LP and CP waves. Moreover, they also generate the OAM waves when illuminated by a CP wave. Finally, the circular phased DMS which can achieve RCSR and generate OAM wave with Mode 2 was fabricated and measured, and the measurement results are in good agreement with the simulation results.