*Question E9B06:
What is the elevation angle of peak response in the antenna radiation pattern shown in Figure E9-2?*  

*Correct Answer is  C: 7.5 degrees*  

### AI Response: (may contain errors)  

To determine the elevation angle of peak response in an antenna radiation pattern, we need to understand how antenna patterns are typically represented and what the peak response indicates.

1. **Correct Answer Explanation (7.5 degrees)**:
   - The peak response in an antenna radiation pattern indicates the angle at which the antenna radiates the most power. In many cases, this is shown in a polar plot or a 3D representation of the radiation pattern.
   - For the given question, the correct answer of 7.5 degrees suggests that the antenna is designed to have its maximum radiation at a relatively low elevation angle, which is common for antennas used in long-distance communication.

2. **Why Other Choices Are Incorrect**:
   - **A: 45 degrees**: This angle is too high for many antennas designed for long-range communication, which often have lower elevation angles to maximize distance.
   - **B: 75 degrees**: This angle is even higher and would typically be associated with antennas designed for short-range or local communication, not for maximizing distance.
   - **D: 25 degrees**: While this angle is lower than 45 and 75 degrees, it is still higher than the peak response indicated in the question. Antennas with a peak at 7.5 degrees are optimized for specific propagation conditions.

3. **Useful Formulas or Rules of Thumb**:
   - Antenna radiation patterns can be analyzed using the concept of the main lobe and side lobes. The main lobe is where the maximum radiation occurs, and its angle can be critical for determining effective communication range.
   - A general rule of thumb is that lower elevation angles are better for long-distance communication, while higher angles are better for local coverage.

In summary, the peak response at 7.5 degrees indicates an antenna optimized for long-distance communication, while the other choices represent angles that are less effective for this purpose.