Dual Circularly Polarized Encoding Terahertz Tag with Linked-Semi-Ellipses Elements

This paper presents a dual circularly polarized encoding terahertz tag utilizing linked-semi-ellipses elements. The proposed design achieves broadband 2-bit polarization encoding in terahertz frequency bands through independently controlling dual circularly polarized phases with linked-semi-ellipses elements. The tag simultaneously possesses two key functionalities: circular polarization conversion and circular polarization encoding, which enhance its resilience to environmental influences. Simulations demonstrated the polarization conversion rates exceeding 80% across 0.42–0.53 THz with reflected RCS from tag achieved −51.7 dB·m2 and a 3 dB beamwidth of ±22°. The tag achieves broadband 2-bit circular polarization encoding and attains a 23.6% relative bandwidth. The circular polarization encoding method enhances stability in metal-rich environments and offers substantial potential for diverse practical applications, including indoor positioning, logistics tracking, and object identification.