*Question G9C01:
Which of the following would increase the bandwidth of a Yagi antenna?*  

*Correct Answer is  A: Larger-diameter elements*  

### AI Response: (may contain errors)  

To understand how to increase the bandwidth of a Yagi antenna, let's analyze the correct answer and the other options.

### Correct Answer: A - Larger-diameter elements

- **Explanation**: Increasing the diameter of the elements in a Yagi antenna reduces the Q factor (quality factor) of the antenna. A lower Q factor results in a wider bandwidth. This is because larger-diameter elements have a lower resistance and can handle a broader range of frequencies without significant loss in performance.

### Why the Other Choices are Incorrect:

- **B: Closer element spacing**: 
  - **Explanation**: Reducing the spacing between elements can actually narrow the bandwidth. Closer spacing increases coupling between elements, which can lead to a higher Q factor and thus a narrower bandwidth.

- **C: Loading coils in series with the element**: 
  - **Explanation**: Loading coils are used to electrically lengthen an antenna, which can increase its resonant frequency. However, they can also introduce losses and increase the Q factor, leading to a narrower bandwidth.

- **D: Tapered-diameter elements**: 
  - **Explanation**: Tapered elements can help with matching and may improve efficiency, but they do not inherently increase bandwidth. The effect on bandwidth can be variable and is generally not as effective as using larger-diameter elements.

### Summary

- **Key Concept**: Bandwidth is inversely related to the Q factor of the antenna. Lowering the Q factor (by using larger-diameter elements) increases bandwidth.
- **Rule of Thumb**: To increase bandwidth in antennas, consider using larger-diameter elements or other methods that reduce the Q factor.

This understanding will help you answer similar questions on the Extra Class exam regarding antenna design and performance.