Collected notes on the topic of radio communications.

Frequencies below 2MHz are reflected off the atmosphere, thus they can follow the Earth's curvature. So these low frequency signals can sometimes be received by radios below the horizon hundreds of miles away. As a general rule, the lower the frequency, the greater distance it can travel. Unlike frequencies below 2MHz, radio waves in higher frequencies(VHF/UHF) travel in straight lines (line-of-sight) generally cannot travel beyond the horizon.

VHF (Very High Frequency)130-174MHz
UHF (Ultra High Frequency)400-520MHz

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