*Question E9C14:
How does the radiation pattern of a horizontally-polarized antenna mounted above a long slope compare with the same antenna mounted above flat ground?*  

*Correct Answer is  B: The main lobe takeoff angle decreases in the downhill direction*  

### AI Response: (may contain errors)  

When a horizontally-polarized antenna is mounted above a long slope, the radiation pattern is affected by the angle of the slope relative to the antenna. 

### Correct Answer Explanation:
- **Correct Answer: B: The main lobe takeoff angle decreases in the downhill direction.**
  
  When the antenna is mounted above a slope, the effective height of the antenna above the ground decreases as you look downhill. This results in a lower takeoff angle for the main lobe of the radiation pattern. Essentially, the antenna radiates more energy at lower angles towards the horizon in the downhill direction, which is beneficial for long-distance communication.

### Incorrect Choices Explanation:
- **A: The main lobe takeoff angle increases in the downhill direction.**
  
  This is incorrect because a slope causes the effective height of the antenna to decrease when looking downhill, leading to a lower takeoff angle, not an increase.

- **C: The horizontal beamwidth decreases in the downhill direction.**
  
  This choice is incorrect because the horizontal beamwidth is primarily determined by the antenna design and not significantly affected by the slope. The beamwidth remains relatively constant regardless of the slope.

- **D: The horizontal beamwidth increases in the uphill direction.**
  
  This is also incorrect. Similar to choice C, the beamwidth is a characteristic of the antenna itself and does not change significantly due to the slope. The slope may affect the effective radiation pattern, but it does not inherently increase the beamwidth.

### Summary:
- The slope affects the effective height of the antenna, which in turn affects the takeoff angle of the main lobe.
- The correct understanding is that the takeoff angle decreases when looking downhill due to the reduced effective height of the antenna.

This knowledge is crucial for understanding how terrain influences antenna performance and propagation characteristics in amateur radio.