Question
What is the front-to-side ratio of the antenna radiation pattern shown in Figure E9-1?
Answer Options
- A) 12 dB
- B) 24 dB
- C) 18 dB
- D) 14 dB
Correct Answer: D
Explanation
The front-to-side (F/S) ratio of a directional antenna measures the rejection of signals arriving from the sides, typically at 90° and 270°. This is important for reducing interference from stations located off to the side of the main beam.
Referring to Figure E9-1, the maximum (peak) gain is at 0°, which is 0 dB. The signal level radiated at the sides (90° and 270°) is approximately -14 dB. The F/S ratio is the difference: 0 dB - (-14 dB) = 14 dB. In general, the front-to-back ratio is often higher than the front-to-side ratio, although not in this specific diagram’s example.
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