Ham Radio General Class Practice Test

The purpose of a "corona ball" on a HF mobile antenna is to reduce high voltage discharge from the tip of the antenna. HF antennas, particularly mobile ones, can develop high voltage at their tips during transmission, which can lead to unintended electrical discharges or "corona" effects. These discharges can create radio frequency interference, reduce efficiency, and potentially damage the antenna or nearby components.

By placing a corona ball at the tip, the design provides a larger and rounded surface area, which helps to dissipate the electrical energy more evenly. This minimizes the peak electric field intensity that occurs at sharp points, hence reducing the likelihood of corona discharge, which can happen when the voltage exceeds the breakdown voltage of the surrounding air. This not only protects the antenna and equipment but also improves the overall performance by ensuring a cleaner signal is transmitted without the disturbances caused by corona effects.