Ham Amateur Radio Technician Practice Exam

What is a characteristic of a random-wire HF antenna connected directly to the transmitter?

1. It requires no tuning

2. Station equipment may carry significant RF current

3. It is not affected by nearby objects

4. It must always be vertically polarized

The correct answer is: Station equipment may carry significant RF current

In the context of a random-wire HF antenna connected directly to the transmitter, the characteristic that stands out is that station equipment may carry significant RF current. A random-wire antenna, due to its un-tuned, non-resonant nature, can lead to a mismatch between the antenna and the transmitter. This mismatch can cause the transmitter to not only send out its intended signal but also reflect a portion of that power back into the equipment, which can result in significant RF currents along the feeding cables and other components of the station. When using a random-wire antenna, the risk of unintended RF feedback or RF energy being present on the station equipment escalates, especially if the connection is not managed carefully. This underscores the importance of using RF isolators and ensuring proper grounding and setup to mitigate these issues. The other characteristics mentioned, while relevant in a broader discussion of antenna properties, do not accurately describe the nature of a random-wire HF antenna as it relates to this specific question. For instance, such antennas typically do require some form of tuning or a matching network to optimize their performance, are often affected by nearby objects due to their radiation pattern, and can be oriented in various ways rather than being restricted to vertical polarization.