Question
What happens as the Q of an antenna increases?
Answer Options
- A) SWR bandwidth increases
- B) SWR bandwidth decreases
- C) Gain is reduced
- D) More common-mode current is present on the feed line
Correct Answer: B
Explanation
The Quality factor (Q) of an antenna system acts similarly to the Q of any resonant circuit, quantifying its selectivity (sharpness) around the resonant frequency. Antenna Q is inversely related to its operational bandwidth.
Therefore, as the Q of an antenna increases, the operating frequency range over which the antenna maintains an acceptable \text{SWR} (the \text{SWR} bandwidth) decreases. Antennas with very high Q (such as highly shortened dipoles or verticals with loading coils) are characterized by being very sharp-tuning and must be re-tuned for small changes in frequency.
This topic was automatically created to facilitate community discussion about this exam question. Feel free to share study tips, memory tricks, or additional explanations!