*Question T9A12:
What is an advantage of a 5/8 wavelength whip antenna for VHF or UHF mobile service?*  

*Correct Answer is  A: It has more gain than a 1/4-wavelength antenna*  

### AI Response: (may contain errors)  

The correct answer to the question about the advantage of a 5/8 wavelength whip antenna for VHF or UHF mobile service is:

**A: It has more gain than a 1/4-wavelength antenna.**

### Explanation of the Correct Answer:
- A 5/8 wavelength whip antenna has a higher gain compared to a 1/4 wavelength antenna. 
- The gain of a 5/8 wavelength antenna is typically around 3 dB greater than that of a 1/4 wavelength antenna. This means it can radiate more power in the desired direction, improving communication range and signal quality.

### Why the Other Choices are Incorrect:
- **B: It radiates at a very high angle.**
  - This is incorrect because a 5/8 wavelength antenna typically radiates at a lower angle compared to a 1/4 wavelength antenna. Lower radiation angles are beneficial for long-distance communication, especially in VHF and UHF bands.

- **C: It eliminates distortion caused by reflected signals.**
  - This statement is misleading. While antenna design can influence how signals are received, no antenna can completely eliminate distortion from reflected signals. The 5/8 wavelength antenna does not specifically address this issue.

- **D: It has 10 times the power gain of a 1/4 wavelength whip.**
  - This is incorrect because the gain of antennas is measured in decibels (dB), not as a direct power ratio. A gain of 10 times power would correspond to 10 dB, which is not the case for a 5/8 wavelength antenna compared to a 1/4 wavelength antenna. The actual gain difference is about 3 dB.

### Useful Formulas and Rules of Thumb:
- The gain of antennas can be compared using the following rule of thumb:
  - A 1/4 wavelength antenna has a gain of approximately 0 dBi (decibels over isotropic).
  - A 5/8 wavelength antenna has a gain of approximately 3 dBi.

This understanding of antenna gain is crucial for optimizing communication in mobile VHF and UHF applications.