How much more power does an HF radio produce compared to VHF/UHF?

• A. About 25 times
• B. About 5 times
• C. About 10 times
• D. About 100 times

Answer: (A)

Long-range communication relies on different propagation paths than short-range, line-of-sight links. HF signals travel by ionospheric reflection, which introduces more loss over distance, so HF transmitters are built to push out more power to ensure the signal remains usable at great ranges. VHF/UHF communications, on the other hand, mainly travel directly between the transmitter and receiver with minimal atmospheric loss, so they don’t need as much power to cover a typical operational radius.

In practical aviation equipment, HF outputs are around a hundred watts or more, while VHF/UHF outputs are typically a few tens of watts. A common rule used in training is that HF provides about 25 times more power than VHF/UHF, which explains why HF can reach distant destinations even when socializing with weak signals.