*Question G3B01:
What is a characteristic of skywave signals arriving at your location by both short-path and long-path propagation?*  

*Correct Answer is  D: A slightly delayed echo might be heard*  

### AI Response: (may contain errors)  

To understand the characteristics of skywave signals arriving via both short-path and long-path propagation, let's analyze the correct answer and the other options.

### Correct Answer: D - A slightly delayed echo might be heard

- **Explanation**: 
  - Skywave propagation involves signals reflecting off the ionosphere. When a signal travels a longer path (long-path) compared to a shorter path (short-path), it can arrive at your location at different times due to the difference in distance traveled.
  - This time difference can create a slight delay, resulting in an echo effect. The longer the path, the more pronounced this delay can be, leading to the perception of a delayed echo.

### Why the Other Choices are Incorrect:

- **A: Periodic fading approximately every 10 seconds**  
  - **Explanation**: While fading can occur in skywave signals, it is not specifically periodic every 10 seconds. Fading is influenced by various factors, including multipath propagation and atmospheric conditions, and does not have a fixed periodicity.

- **B: Signal strength increased by 3 dB**  
  - **Explanation**: A 3 dB increase in signal strength typically indicates a doubling of power or an increase in gain. However, this is not a characteristic of skywave propagation. The signal strength can vary due to many factors, but it does not inherently increase by a fixed amount like 3 dB due to the nature of the propagation paths.

- **C: The signal might be cancelled causing severe attenuation**  
  - **Explanation**: While cancellation can occur due to destructive interference when signals arrive out of phase, this is not a defining characteristic of skywave signals arriving via both paths. It can happen, but it is not guaranteed and does not describe the typical behavior of skywave signals.

### Summary

- The correct answer highlights the unique aspect of skywave propagation where signals can arrive at different times, creating a delayed echo.
- The other options either misrepresent the nature of skywave propagation or introduce concepts that are not consistently applicable.

This understanding is crucial for the Extra Class exam, as it emphasizes the behavior of radio waves in different propagation scenarios.