Ace the ATPL Communication Challenge 2025 – Fly High with Confidence!

Ionospheric attenuation is a phenomenon that occurs when radio signals pass through the ionosphere, which is a layer of the Earth's atmosphere that is ionized by solar and cosmic radiation. This attenuation can vary significantly across different frequency ranges.

In the case of low frequency signals, which typically range from 30 kHz to 300 kHz, the ionosphere reflects or refracts these frequencies very well when conditions are right. Attenuation tends to be lower for signals in this range, allowing for long-distance communication. However, as we move to higher frequencies such as those in the medium frequency (MF) and high frequency (HF) ranges, the ionosphere starts to absorb more of the energy from the signals.

At very high frequencies (VHF), the ionosphere becomes less reflective, and most signals can penetrate through it rather than being reflected back to the Earth's surface. This is why VHF communications are largely line-of-sight and not greatly affected by ionosphere changes.

The correct answer reflects that at low frequency, the ionosphere is less efficient in retaining and propagating signals, and therefore ionosphere attenuation is minimized rather than maximized. Hence, in higher frequency bands, especially those above the medium range, the ionospheric absorption