Ham Radio General Class Test 2026 – 400 Free Practice Questions to Pass the Exam

Long distance communication on the 40, 60, 80, and 160 meter bands is indeed more challenging during the day primarily because of the behavior of the D layer of the ionosphere. When the Sun is shining, it ionizes the upper atmosphere, creating the D layer. This layer is responsible for absorbing radio waves in the lower frequency ranges, which includes the frequencies used by these bands. As a result, signals attempting to propagate over long distances during daylight can be significantly weakened or completely absorbed by this layer, leading to poor communication efficacy.

The other options pertain to different layers of the ionosphere and their characteristics. The F layer, for instance, becomes more effective for higher frequency communication at night, while the E layer's stability does not directly relate to the specific challenges faced by these lower bands during daylight. Understanding the role of the D layer in absorption helps clarify why lower frequency communication becomes difficult when the sun is up.