*Question E3B12:
What is chordal-hop propagation?*  

*Correct Answer is  B: Successive ionospheric refractions without an intermediate reflection from the ground*  

### AI Response: (may contain errors)  

Chordal-hop propagation refers to a specific type of radio wave propagation that occurs when signals are refracted through the ionosphere multiple times without reflecting off the ground in between. 

### Explanation of the Correct Answer:
- **Correct Answer: B: Successive ionospheric refractions without an intermediate reflection from the ground.**
  - In chordal-hop propagation, radio waves can travel long distances by being refracted through the ionosphere multiple times. This allows the signals to "hop" from one layer of the ionosphere to another, effectively extending their range without bouncing off the Earth's surface. This is particularly useful for long-distance communication.

### Explanation of Incorrect Answers:
- **A: Propagation away from the great circle bearing between stations.**
  - This describes a general propagation phenomenon but does not specifically relate to the mechanism of chordal-hop propagation. Chordal-hop propagation is not defined by the direction relative to the great circle but rather by the method of ionospheric refraction.

- **C: Propagation across the geomagnetic equator.**
  - While propagation can be affected by the geomagnetic equator, this choice does not accurately describe chordal-hop propagation. Chordal-hop is more about the multiple refractions in the ionosphere rather than the geographic or magnetic positioning of the stations.

- **D: Signals reflected back toward the transmitting station.**
  - This describes a scenario where signals are reflected, which is not the case in chordal-hop propagation. In chordal-hop, the signals are refracted, not reflected, allowing them to travel further distances.

### Summary:
- Chordal-hop propagation is characterized by multiple ionospheric refractions without ground reflection, making it effective for long-distance communication.
- Understanding the differences between these propagation methods is crucial for the Extra Class exam, as it helps in grasping how radio waves behave under various atmospheric conditions.