在无线电通信中,电波传播是一个主要环节。在建立通信电路时,合适地选择频率和电波传播的方式是极为重要的,合理的选择就保证了电路的畅通和经济性。早在本世纪三十年代,人们就已经掌握和使用了:(1)长波和中波沿着地球表面的传播;(2)短波经过电离层反射的传播;(3)超短波在视距范围内的传播等电波传播的方式。近年来,由于成功地发射了人造地球卫星和实现了大功率的发信机、高增益天线和高灵敏度的接收机,相继出现了许多新的传播方式,对流层 In radio communications, radio waves are a major link. In the establishment of communication circuits, the appropriate choice of frequency and wave propagation is extremely important, a reasonable choice to ensure the circuit flow and economy. As early as the 1930s, people have mastered and used: (1) longwave and mediumwave propagation along the Earth’s surface; (2) shortwave propagation through ionospheric reflections; (3) ultrashortwave within the line-of-sight The spread of radio waves and other means of communication. In recent years, due to the successful launch of man-made earth satellites and the realization of high-power transmitters, high-gain antennas and high-sensitivity receivers, there have been many new modes of propagation. The troposphere