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

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

• A. Tropospheric ducting
• B. Fading
• C. Multi-path interference
• D. Sporadic E

Answer: (D)

Sporadic E propagation refers to a phenomenon where radio signals can travel unusually long distances due to the creation of ionized layers in the ionosphere. This occurs primarily in the E region of the ionosphere and is characterized by the ability to reflect signals over considerable distances, especially on the 10, 6, and 2 meter bands. This type of propagation creates strong signals that can come and go, resulting in the occasional strong contacts you would experience when conditions are favorable, such as during summer months. In contrast, tropospheric ducting involves the bending of radio waves in the troposphere caused by temperature inversions and can also result in long-distance communication, but it is less common compared to Sporadic E. Fading refers to variations in signal strength caused by atmospheric conditions or physical obstacles, rather than long-distance propagation. Multi-path interference occurs when signals travel different paths to reach the receiver, causing potential distortion or signal degradation rather than long-range communication. Understanding these differences highlights how Sporadic E is key to achieving long-range contacts on certain VHF bands, making it the correct answer in this context.

Sporadic E propagation refers to a phenomenon where radio signals can travel unusually long distances due to the creation of ionized layers in the ionosphere. This occurs primarily in the E region of the ionosphere and is characterized by the ability to reflect signals over considerable distances, especially on the 10, 6, and 2 meter bands. This type of propagation creates strong signals that can come and go, resulting in the occasional strong contacts you would experience when conditions are favorable, such as during summer months.

In contrast, tropospheric ducting involves the bending of radio waves in the troposphere caused by temperature inversions and can also result in long-distance communication, but it is less common compared to Sporadic E. Fading refers to variations in signal strength caused by atmospheric conditions or physical obstacles, rather than long-distance propagation. Multi-path interference occurs when signals travel different paths to reach the receiver, causing potential distortion or signal degradation rather than long-range communication.

Understanding these differences highlights how Sporadic E is key to achieving long-range contacts on certain VHF bands, making it the correct answer in this context.