Design of a 3-D Printed Wideband Circularly Polarized Teraherts Fresnel Lens Antenna

The terahertz (THz) band is critical for 6G systems, yet high-gain circularly polarized (CP) antennas remain challenging due to fabrication and performance constraints. This work presents a compact 3D-printed THz lens antenna at 300 GHz, combining a Fresnel lens and triangular polarizer to achieve wideband CP and low profile. The Fresnel lens reduces height and loss, while the polarizer enables 90° phase shifts for CP via anisotropic dielectric unit cells. Fabricated with High Temp V2 material, measurements show 40% impedance bandwidth (220–330 GHz), 26.4 dB peak gain, and 28.7% axial ratio bandwidth. Measurements confirm collimated beams with −20 dB sidelobes, gain alignment with simulations with almost no gain gap. The design demonstrates the viability of 3D-printed CP antennas for 6G, balancing performance and manufacturability.