A Survey on Advancements in THz Technology for 6G: Systems, Circuits, Antennas, and Experiments

Terahertz (THz) carrier frequencies (100 GHz to 10 THz) have been touted as a source for unprecedented wireless connectivity and high-precision sensing, courtesy of their wide bandwidth availability and small wavelengths. However, noteworthy implementation challenges persist, ranging from limitations in semiconductor device technologies to antenna design and packaging, as well as system-level issues such as high path loss, complex beam management, and regulatory constraints. In this paper, we survey recent advancements on 6G networks using THz frequencies, with a particular emphasis on the 200–400 GHz frequency range and the IEEE 802.15.3d standard. This band offers a compelling balance by providing ample bandwidth for high data-rate communications, while also exhibiting lower atmospheric absorption for longer-range transmission, and can be viably realized using current semiconductor technologies. Unlike other existing surveys in this domain, we provide a comprehensive and holistic overview of THz systems, circuits, device technology, and antennas while also highlighting recent experimental demonstrations of 6G networks using THz frequencies. Throughout this paper, we review the state-of-the-art in 6G network implementation using THz, and call attention to open problems, future prospects, and areas of further improvement in THz communication technologies to fully realize their potential in next-generation wireless connectivity.