The fifth-generation mobile communication system has been officially commercialized. The transmission rate of 5G should be more than ten times faster than that of 4G, that is, the transmission rate of 5G can achieve 1Gb/s. There are basically two methods for wireless transmission to increase the transmission rate. One is to increase the spectrum utilization, and the other is to increase the spectrum bandwidth. Compared with improving the spectrum utilization, the method of increasing the spectrum bandwidth is simpler and more direct. The commonly used frequency bands below 5GHz are already very crowded. In order to find new spectrum resources, the method that comes to mind is to use mm wave technology.
Microwave bands include: decimeter waves, centimeter waves, MM waves and submilimeter waves. Among them, MM waves usually refer to electromagnetic waves with a frequency range of 30 to 300 GHz and a corresponding wavelength of 1 to 10 mm. Its operating frequency is between microwave and far-infrared waves, so it has the characteristics of both spectrums. The theory and technology of MM wave are the extension of microwave to high frequency and the development of light wave to low frequency.
Since the "General Theory of Electromagnetism" in 1873, people have done a lot of work in broadening the tiles by making full use of electromagnetic resources. The research on MM waves was proposed as early as 1889, and it has been a long time for a century. The development of MM waves has been up and down, but the research on MM waves has always attracted many scholars, who have gained a lot of basic knowledge. Research on MM waves must be supported by corresponding technologies, so research in this field has been relatively slow, and it can be said that there have been twists and turns. However, with the development of corresponding technologies and when infrared and visible light technologies cannot provide the best solutions in some important occasions, MM waves have become increasingly prominent due to their characteristics that are different from ordinary microwaves.
Until now, due to the successful development and mass production of millimeter-wave integrated circuits and millimeter-wave solid-state devices, the production cost has been declining, and millimeter-wave communications have flourished like dead trees in spring. With the advancement of science and technology, MM wave communications will surely show broad application prospects.