Ultra-wideband reflective polarization rotator achieving 104% measured bandwidth with high-efficiency multi-state...

This article introduces a compact ultra-wideband reflective polarization rotator, covering 12.68-38.79 GHz, which offers notable linear-to-elliptical, linear, and circular polarization conversion. The metasurface comprises a semi-octa-circular copper layout on an F4BM220 substrate with a unit cell size of 5mm×5mm×2mm backed by a ground plane, configured to facilitate four strong resonances enabling highly precise polarization rotation within Ku, K, and Ka bands. Unlike traditional symmetric polarization rotators, the proposed hybrid octa-circular geometry incorporates a rectangular cutout that triggers Omega-type bianisotropy, extending the operational fractional bandwidth to 104%. Full-wave simulations exhibit a -10 dB rotational bandwidth (RBW) of 112.16% using Generalized Sheet Transition Conditions (GSTC) analysis, while experimental measurements of the fabricated 60× 60 unit cell array feature an RBW of 104.76%, demonstrating superior real-world performance. The rotator sustains polarization conversion efficiency exceeding 91% and exhibits stable functionality for oblique incidence up to 30[Formula: see text]. Concordance between theory and experimental observations is validated through CST-analysis, Bi-Mode Foster Equivalent Circuit analysis, and laboratory measurements. Ultra-wideband operation, compact size, strong resonances, high PCR, and multi-state polarization response highlight the novelty of the design and ensure suitability for radar imaging, sensing, satellite communications, and emerging 6G systems.