What primarily determines a radar's range resolution?

• A. Transmitter frequency stability
• B. Antenna beamwidth
• C. Pulse width and bandwidth
• D. Receiver dynamic range

Answer: (C)

Range resolution is how closely two targets at different distances along the line of sight can be distinguished. This is set mainly by the transmit pulse’s time length and its bandwidth. A shorter pulse or a signal with greater bandwidth yields a shorter return-time window, so echoes from closely spaced targets don’t blur together. The practical relationship is ΔR ≈ cτ/2, where τ is the pulse width, and increasing bandwidth also tightens ΔR because a wider spectrum corresponds to a shorter effective pulse in time (ΔR ≈ c/(2B)).

Other factors don’t determine this spacing: transmitter frequency stability affects frequency precision and Doppler measurement rather than how closely two range echoes can be separated; antenna beamwidth governs angular, not range, resolution; receiver dynamic range impacts the ability to detect signals but not the minimum separable distance in range.