Terahertz lens antennas

While the transition from the fourth generation (4G) to the fifth generation (5G) wireless communications is slowly taking place around the world, researchers are already charging ahead on the sixth generation (6G) in which the terahertz (THz) spectrum will be utilized for delivering big data services that are yet to be foreseen. In addition to ultrahigh-speed communications, the THz spectrum also has many other applications such as high-resolution imaging and non-destructive detections. The increase of the operating frequency imposes significant challenges in THz antenna design due to the high atmospheric loss of wave propagation, significant metal and dielectric material losses, and limited fabrication tolerances. In this chapter, we address these challenges by developing phase modulation techniques to design THz lens antennas. Discrete dielectric lenses (DDLs) are an appealing high-gain THz antenna candidate, owing to their advantageous characteristics such as low loss, simple feeding networks, arbitrary aperture phase control, and ease of fabrication. Moreover, we utilize inexpensive 3D printing technology and the superior geometric flexibility it provides to design and fabricate novel DDL antennas that can generate high-gain linearly-polarized (LP) far-field radiation at 0.3 THz. By integrating the THz LP far-field lens with a 3D printed dielectric grating, circularly-polarized (CP) radiation is then demonstrated. Modifications to the phase modulation at the lens aperture allow us to achieve focused LP and CP beams for THz imaging applications. In near-field ultrahigh-speed data exchange, a high intensity focused beam over a considerable distance is preferred and a THz Bessel beam launcher is realized to address this need. A non-diffractive higher order THz Bessel beam carrying orbital angular momentum (OAM) for channel capacity enhancement is also demonstrated. © 2022 The Institute of Electrical and Electronics Engineers, Inc.