从电波传播理论可知:VHF信道是一种传播比较稳定的恒参信道,也叫做视距传播信道.从VHF发射天线上辐射出来的电波,是一种超短波,其频率范围在30-300MHZ,能穿透电离层而无法返回地面,但能用对流层传播.其传播距离受到地球曲率等因素的影响,收、发通信间最大距离被限制在视线范围以内,通常这种信道的传播最大距离为几十到100公里范围以内. From radio wave propagation theory we can see: VHF channel is a more constant propagation constant channel, also known as line-of-sight propagation channel. Radiated from the VHF transmitting antenna on the radio waves, is a kind of ultrashort wave, the frequency range of 30-300MHZ, Penetrate the ionosphere and can not return to the ground, but can be transmitted using the troposphere. Its propagation distance by the Earth’s curvature and other factors, the maximum distance between the receiving and sending communications is limited to the line of sight range, usually such channel maximum distance Within ten to 100 kilometers range.