Beam Manipulation for Terahertz Communications: A New Quality Productive Force

Abstract: The terahertz frequency band, ranging from 0.1 to 10 THz, offers extensive spectral resources for next-generation wireless communication systems. To compensate for the limited transmission power of terahertz transceivers and the significant propagation losses in terahertz channels, high-gain directional antennas are essential. Dynamic beam manipulation is therefore crucial for enabling practical communication applications. Moreover, the stringent gain requirements in terahertz systems result in an expanded Fresnel region, highlighting the critical need for efficient beam manipulation techniques in both near-field and far-field conditions. This article provides a comprehensive overview of terahertz beam manipulation techniques. It begins with an introduction of diffraction theory as the foundational propagation model for beam manipulation. Detailed examples tailored to specific communication scenarios are then presented. Experimental verifications using 3-D printed lenses are included for three distinct beam manipulation cases. Alternative approaches for achieving beam manipulation, such as metasurfaces and reconfigurable intelligent surfaces, are briefly discussed.