Ham Radio General Class Practice Test

What is one disadvantage of a directly fed random-wire antenna?

1. It must be longer than 1 wavelength

2. You may experience RF burns when touching metal objects in your station

3. It produces only vertically polarized radiation

4. It is not effective on the higher HF bands

The correct answer is: You may experience RF burns when touching metal objects in your station

One notable disadvantage of a directly fed random-wire antenna is the risk of experiencing RF burns when touching metal objects in your station. This phenomenon occurs because a directly fed antenna can have high RF voltages present on its elements, especially if the feedline is not properly balanced or if the antenna is not designed to be isolated from nearby conductive objects. As a result, touching elements of the station or even nearby conductive surfaces while transmitting can lead to increased exposure to RF energy, potentially causing burns. Regarding the other options, while a random-wire antenna does not necessarily have to be longer than 1 wavelength, it can be effective even if it is shorter, though performance might vary. Random-wire antennas can also radiate horizontally polarized waves, depending on their configuration and orientation, making the statement about producing only vertically polarized radiation inaccurate. Additionally, while their efficiency may decrease on higher HF bands, this is not universally the case, as many designs can still perform adequately if properly tuned and matched. Therefore, the concern about RF exposure makes the second option particularly significant.