Ham Amateur Radio Technician Practice Exam

In which direction is the maximum radiation from a VHF/UHF "halo" antenna?

1. Unidirectional along the boom

2. Omnidirectional in the plane of the halo

3. Directional towards the horizon

4. Bidirectional vertically

The correct answer is: Omnidirectional in the plane of the halo

The maximum radiation from a VHF/UHF "halo" antenna is omnidirectional in the plane of the halo. This means that the antenna radiates signals evenly in all directions within the horizontal plane, providing coverage across 360 degrees. Halo antennas are a type of loop antenna that are designed to operate efficiently in the VHF and UHF bands. Their construction allows them to have low angle radiation and minimal polarization, which contributes to their omnidirectional pattern in the horizontal plane. This characteristic makes them particularly useful for applications where uniform signal distribution is desired, enabling reliable communication with stations in various directions. Other options described do not accurately represent the radiation pattern of a halo antenna. For example, a unidirectional pattern along the boom would suggest focused transmission in one direction, which is not typical for halo configurations. Similarly, while antennas can be designed for directional radiation towards the horizon, a halo does not focus energy in that manner. A bidirectional vertical pattern suggests that there would be maximum radiation at two opposite points, which is not representative of the consistent horizontal coverage that a halo provides.