Starting from the Shenzhou 5 manned spacecraft that inspired the whole country, China's aviation has entered the fast lane of development. Some curious friends asked, with so many satellites in the sky, how do they "communicate" with each other? In space, two satellites are in Earth orbit, and it takes a while to complete data transmission using traditional satellite technology. However, the emergence of terahertz technology allows satellites to "communicate" quickly without having to "work overtime."

Technology applied to achieve rapid "dialogue" between satellites

On November 6, 2020, my country successfully launched the world's first 6G test satellite "University of Electronic Science and Technology of China" at the Taiyuan Satellite Launch Center Number". Why is it called 6G experimental satellite? The key is that this satellite is equipped with terahertz communication equipment. It is terahertz communication equipment that allows wider and faster roads to transmit data between satellites.

What is terahertz? What are the advantages of terahertz?

This introduces a new concept - terahertz. You may be unfamiliar with terahertz. From a scientific definition, terahertz radiation is electromagnetic radiation of 0.1~10THz. To put it in a familiar way, the two brothers adjacent to the terahertz band on the electromagnetic spectrum are the infrared in the remote control and the microwave in the microwave oven. Sandwiched between infrared and electromagnetic waves is terahertz.

Because the frequency band is neither suitable for optical theoretical processing nor completely suitable for microwave theoretical research, terahertz technology has become an almost blank technical field for a long period of time. However, through the efforts of scientists, they have discovered the advantages of terahertz compared to other frequency bands, because terahertz integrates the advantages of microwave communication and optical communication, and has high transmission rate, large capacity, strong directionality, high security and penetration. It has many characteristics such as good permeability, so terahertz also has its own "status in the world."

In what other fields can terahertz be used in the future?

Professor Li Shaoqian, a well-known expert in the field of China Mobile Communications, introduced that terahertz is a new generation of communication technology. One is traditional terrestrial large-capacity communication and may be the future 6G technology. The other is used in aerospace. Spatial high-capacity communication in the field.

The frequency band used by terahertz communication technology is between 0.1THz and 10THz, and the current mainstream communication band in the world is between 0.1THz and 1THz. This means that the spectrum resources in the terahertz frequency band are more abundant, and once applied in the communication field, faster information transmission with greater capacity can be achieved.

Due to the characteristics of high frequency and strong beam directivity of terahertz, mobile access and coverage of terahertz equipment are difficult and have shortcomings of short transmission distance. As the saying goes, "short is better than short." For the industrial field and even the military field, given the complexity of application scenarios, the limited transmission distance can actually become an advantage, making communication smoother and safer.

With the development of science and technology, terahertz technology, as the forefront of communication technology, will gradually enter thousands of households. For terrestrial mobile communications, although terahertz has its own limitations, it complements the advantages of 4G/5G and will definitely play a greater role in promoting technological progress and communication development, especially in industrial applications. I believe it will be able to achieve great success in the future. The earth changes the structure of industrial production. Although 6G technology deserves our excitement, we must also view technology dialectically and do our best to make technology benefit mankind by seeking advantages and avoiding disadvantages.

Expert: Yu Xinle, associate researcher majoring in signal and information processing at Communication University of China