Barbell-Shaped Reflective Metasurface for Broadband Linear-to-Circular Polarization Conversion in K, Ka, and V Bands

In this work, a novel barbell-shaped reflective Polarization Conversion Meta-Surfaces (PCMS) is designed and comprehensively analyzed for ultra-wideband and linear-to-circular polarization conversion (LCPC) with excellent efficiency. The proposed PCMS works in reflection mode and meets the 3-dB Axial Ratio criterion within a very wide frequency range from 15 GHz to 50 GHz, thus giving an exceptionally large fractional bandwidth of 89.67%. Several resonant modes determine the polarization conversion mechanism; at 19.7 GHz, 31.8 GHz, and 44.3 GHz, the PCR approaches 100%. The metasurface consists of compact unit-cell dimensions with lateral sizes of 0.2λ₀ × 0.2λ₀ (4 mm × 4 mm) and a substrate thickness of 0.4333λ₀, where λ₀ represents wavelength in free space at the lowest frequency of operation. The proposed PCMS has a very low insertion loss (< 0.3 dB) and maintains stable Axial Ratio and phase response for the incidence angles up to 20°, confirming strong angular stability and robust polarization conversion performance. Owing to its compact geometry, fabrication simplicity, and superior broadband characteristics, For K, Ka, and V bands millimeter-wave antenna systems, the suggested barbell-shaped PCMS is a viable option.