*Question G9D03:
In which direction is the maximum radiation from a VHF/UHF “halo” antenna?*  

*Correct Answer is  C: Omnidirectional in the plane of the halo*  

### AI Response: (may contain errors)  

A VHF/UHF "halo" antenna is a type of horizontally polarized antenna that is often used for mobile and portable operations. It is essentially a loop antenna that is designed to be compact and have an omnidirectional radiation pattern in the horizontal plane.

### Explanation:

1. **Correct Answer: C - Omnidirectional in the plane of the halo**
   - A halo antenna is designed to have an omnidirectional radiation pattern in the plane of the loop. This means that it radiates equally well in all directions around the loop when viewed from above. This characteristic makes it ideal for mobile operations where the direction of the signal source can change frequently.

2. **Why the Other Choices are Incorrect:**
   - **A: Broadside to the plane of the halo**
     - This would imply that the maximum radiation is perpendicular to the plane of the loop, which is not the case for a halo antenna. The radiation is strongest in the plane of the loop, not broadside to it.
   - **B: Opposite the feed point**
     - This suggests a directional pattern with a null at the feed point and maximum radiation opposite it. However, a halo antenna is designed to be omnidirectional, not directional.
   - **D: On the same side as the feed point**
     - Similar to choice B, this implies a directional pattern, which is not characteristic of a halo antenna. The radiation pattern is uniform around the loop, not concentrated on one side.

### Key Points:
- **Omnidirectional Pattern:** The halo antenna's design ensures that it radiates equally in all directions in the plane of the loop, making it effective for receiving and transmitting signals from any direction.
- **Horizontal Polarization:** The halo antenna is horizontally polarized, which can be advantageous for certain types of communication, especially in VHF/UHF bands.

Understanding the radiation pattern of different antennas is crucial for selecting the right antenna for your needs and ensuring effective communication.