What effect does a longer pulse width have on radar detection?

• A. Permits longer ranges and enhances display of smaller targets
• B. Increases minimum range
• C. Reduces resolution
• D. Degrades detection of weather

Answer: (C)

Longer pulse width means the radar is transmitting energy for a longer time with each pulse, which stretches the range “slice” used to separate echoes. The range resolution, which determines how close two targets can be in range and still be distinguished, is tied to the pulse duration and can be approximated by ΔR ≈ cτ/2. Increasing τ makes ΔR larger, so echoes from targets that are close together in range merge and the radar can’t resolve them as separate targets. This is why a longer pulse width reduces resolution. While longer pulses do carry more energy and can aid detection of isolated targets at greater distances, the primary effect on detecting and distinguishing targets is the loss of range resolution.