1. Problem description:
With the continuous development of communication technology, the existing communication system has been unable to meet the needs of people in all aspects. In order to solve this problem, 5G communication technology has emerged. 5G technology has a higher communication transmission rate, a larger communication range and a higher efficiency of spectrum use. The key to 5G communication technology is millimeter wave technology. Millimeter wave communication technology has the advantages of strong real-time performance and long transmission distance.
Due to the presence of a certain amount of polarized oxygen molecules and water vapor in the atmosphere, millimeter waves are easily absorbed by the atmosphere during transmission, which leads to signal attenuation and affects communication quality [13,14]. According to relevant research findings, in some special frequency bands, such as 60GHz, 119GHz, and 183GHz, this effect is more serious. In practice, the use of these frequency bands should be prevented. In some other frequency bands, the communication performance is better, such as 35GHz, 140GHz, 220GHz and so on. Figure 3.1 shows the atmospheric attenuation trends of millimeter waves in different frequency bands.