The sub-terahertz (sub-THz) spectrum refers to a part of the electromagnetic spectrum that falls between mmWave and terahertz frequencies, typically ranging from approximately 100 GHz to 1 THz. This spectrum is of great interest for various applications, including wireless communications, imaging, and sensing technologies. This band is getting attention especially for 6G communication.
The sub-THz spectrum represents an exciting frontier for various scientific and technological fields, promising to unlock new capabilities in high-speed communications, imaging, and sensing. However, harnessing its potential also poses significant technical challenges that are the focus of current research and development efforts.
Followings are some well-known bands within the sub-terahertz spectrum:
D Band
- Frequency Range: The D Band extends from 110 GHz to 170 GHz.
- Applications: This band is particularly interesting for high-speed, short-range wireless communication systems. The wide bandwidth available in the D Band can support data rates of several tens of Gbps (Gigabits per second), making it suitable for future wireless networks (e.g., 6G) that aim to provide ultra-high-speed data services. It's also being explored for high-resolution imaging and radar systems.
- Challenges: The main challenges include signal attenuation due to atmospheric absorption (mainly by water vapor) and technological hurdles related to the generation, modulation, and detection of high-frequency signals. Developing cost-effective and energy-efficient components (such as amplifiers, antennas, and transceivers) for this band requires advances in semiconductor materials and integrated circuit technologies.
G Band
- Frequency Range: The G Band covers frequencies from 140 GHz to 220 GHz.
- Applications: It finds applications in both communication and non-communication areas. In telecommunications, the G Band is considered for ultra-high-speed wireless links that could serve as backhaul for mobile networks or for connecting devices in data-intensive environments (like data centers). It's also used in remote sensing, particularly for atmospheric and environmental studies, due to its sensitivity to water vapor and other atmospheric gases.
- Challenges: Similar to the D Band, the G Band faces issues with atmospheric losses and technical difficulties in equipment design. The higher the frequency, the more significant the challenges with material and device engineering to achieve efficient signal transmission and reception.
H Band
- Frequency Range: The H Band spans from 220 GHz to 325 GHz.
- Applications: This band is on the frontier of sub-THz research, pushing into frequencies that are less explored for commercial applications. Potential uses include very high-resolution radar, such as for security screening and scientific applications, including spectroscopy for chemical analysis. In telecommunications, it represents an area for future exploration, possibly for extremely high-throughput, short-distance links.
- Challenges: Operating in the H Band amplifies the difficulties encountered in lower sub-THz bands. The atmospheric absorption is even higher, and the technology for efficiently generating and detecting signals at these frequencies is more complex and less mature. Research in materials science, particularly in developing semiconductors that can operate efficiently at these frequencies, is critical.