Which type of frequency is least impacted by terrain and is cleared for line of sight transmission?

The VHF (Very High Frequency) band is the type of frequency least impacted by terrain and is suitable for line-of-sight transmission. The reason for this characteristic is that VHF frequencies, which usually range from 30 MHz to 300 MHz, have longer wavelengths that enable them to travel relatively well over uneven terrain compared to higher frequency bands.

VHF signals can be effectively transmitted over distances limited largely by the curvature of the Earth and the antenna height. This makes them ideal for communications in aviation, as aircraft can maintain clear communication in the range of VHF despite changes in terrain. The line-of-sight nature of VHF means that it is typically effective in maintaining strong communication links as long as there aren’t significant obstructions between the transmitting and receiving antennas.

In contrast, other frequency types have different characteristics that make them more susceptible to terrain effects or operational limitations. HF (High Frequency) operates at lower frequencies, which can reflect off the ionosphere and allows for long-distance transmission but could also lead to unpredictability in communication due to varying atmospheric conditions. UHF (Ultra High Frequency) is used for services requiring high bandwidth, but it is more affected by terrain and has a shorter range compared to VHF. NDB (Non-D