ARRL Technician Practice Exam

Which of the following propagation types is most commonly associated with occasional strong over-the-horizon signals on the 10, 6, and 2 meter bands?

1. Sporadic E

2. F layer

3. Tropospheric scatter

4. Continuous wave

The correct answer is: Sporadic E

Sporadic E propagation is characterized by occasional, short-lived openings that allow radio signals to travel over distances greater than what is normally expected for the given frequency. This type of propagation is particularly significant on the 10, 6, and 2 meter bands, where signals can occasionally bounce off ionized patches of the E layer of the atmosphere. These patches can reflect signals over long distances, resulting in strong over-the-horizon communications during certain times of the year, especially in the summer months. Understanding the nature of Sporadic E propagation is key for amateur radio operators, as it can greatly extend the range of communications beyond the normal line-of-sight that would typically apply to VHF and UHF bands. The phenomenon is unpredictable, but when it does occur, it can lead to excellent propagation conditions for several minutes to hours, enabling contact with stations that would normally be too far away to reach. Other options describe different types of propagation: the F layer primarily contributes to longer-range HF communications, tropospheric scatter occurs for VHF frequencies but is generally less effective at shorter distances compared to sporadic openings, and continuous wave refers to a type of transmission rather than a form of propagation. Therefore, the identification of Sporadic E as the correct