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高频通信一直是无线电通信的重要环节,五十年代达到了其鼎盛时期。不过事物总有两面性,与此同时,其一系列固有的缺点也充分暴露了。由于高频频段频谱窄,用户一多,频道就很拥挤,相互干扰严重。大家知道,高频波是依靠电离层反射来传播的,受太阳活动、大气变化等一些天文和气候现象的影响较重,传输不太稳定,此外还
High-frequency communications has always been an important part of radio communications and reached its heyday in the 1950s. However, things always have two sides, at the same time, a series of inherent shortcomings have also been fully exposed. Due to the narrow spectrum of the high-frequency band and the large number of users, the channel is very crowded and the mutual interference is serious. We all know that high-frequency waves are propagated by ionospheric reflections and are affected by some astronomical and climatic phenomena such as solar activity and atmospheric changes. The transmission is not very stable. In addition,