ATPL EASA Radio Navigation Practice Exam 2025 - Free Radio Navigation Practice Questions and Study Guide

The correct range for High Frequency (HF) radio waves is indeed 100 m to 1 m. HF frequencies fall within the range of 3 MHz to 30 MHz, which correlates to wavelengths from approximately 100 m to 10 m. The wavelength is inversely proportional to the frequency; therefore, as frequency increases, the wavelength decreases.

Choosing this option highlights an understanding of how radio frequency bands are categorized based on their wavelength. The HF band is particularly significant in aviation for long-distance communication due to its ability to ionize the upper atmosphere, which allows HF radio waves to be reflected back to Earth, enabling worldwide communication.

The other wavelength ranges provided do not correspond correctly to the High Frequency category. This includes the ranges that either fall outside the HF spectrum or span frequencies that belong to different classifications, such as VHF (Very High Frequency) or UHF (Ultra High Frequency). Thus, recognizing the correct range is crucial for comprehension of HF radio systems and their application in aviation navigation and communication.