*Question G9C07:
What does “front-to-back ratio” mean in reference to a Yagi antenna?*  

*Correct Answer is  C: The power radiated in the major lobe compared to that in the opposite direction*  

### AI Response: (may contain errors)  

The "front-to-back ratio" of a Yagi antenna is an important parameter that indicates how effectively the antenna radiates in its intended direction compared to the opposite direction.

### Correct Answer Explanation:
- **C: The power radiated in the major lobe compared to that in the opposite direction**  
  This is correct because the front-to-back ratio quantifies the difference in power radiated in the direction of the main lobe (the direction the antenna is pointed) versus the power radiated in the opposite direction (back lobe). A higher front-to-back ratio means that the antenna is more directional and has better performance in its intended direction.

### Incorrect Answer Explanations:
- **A: The number of directors versus the number of reflectors**  
  This is incorrect because the front-to-back ratio does not directly relate to the count of directors and reflectors. While more directors can improve gain and directivity, the front-to-back ratio specifically measures power distribution rather than element count.

- **B: The relative position of the driven element with respect to the reflectors and directors**  
  This is incorrect because the position of the driven element affects the antenna's overall performance and impedance but does not define the front-to-back ratio. The ratio is about power radiation in different directions, not element positioning.

- **D: The ratio of forward gain to dipole gain**  
  This is incorrect because the front-to-back ratio is not a comparison of forward gain to dipole gain. Instead, it focuses on the power radiated in the forward direction versus the backward direction, which is a different concept.

### Summary:
The front-to-back ratio is a key performance metric for Yagi antennas, indicating how well the antenna focuses energy in the desired direction compared to the opposite direction. A higher ratio is generally desirable for effective communication.

### Useful Rule of Thumb:
- A front-to-back ratio of 10 dB means that the power radiated in the forward direction is 10 times greater than that in the backward direction. This can be expressed as:

$$
\text{Front-to-Back Ratio (dB)} = 10 \log_{10} \left( \frac{P_{\text{forward}}}{P_{\text{backward}}} \right)
$$

Where:
- $P_{\text{forward}}$ = power radiated in the forward direction
- $P_{\text{backward}}$ = power radiated in the backward direction

Understanding this concept will help you grasp the performance characteristics of Yagi antennas and their applications in amateur radio.