Radar Range Resolution
Smallest separation at which two targets appear as distinct echoes, set by the transmitted pulse width.
Formula
Variables
Example
1 µs pulse: ΔR = 3×10⁸×10⁻⁶ ÷ 2 = 150 m
How it works
Radar range resolution tells you how far apart two targets must be before the radar can separate their echoes into two distinct returns. It depends on pulse width because a longer pulse occupies more distance in space, so the returned echoes overlap more easily; the factor of 2 appears because the radar signal travels to the target and back, so the pulse length is split between outbound and return path distance. In effect, a shorter transmitted pulse gives better ability to distinguish targets that are close together in range.
When to use it
Use this formula when you need to estimate the minimum spacing in distance that a pulsed radar can resolve between two objects. It is especially useful in radar system design, target detection analysis, and comparing how pulse duration affects imaging or surveillance performance.
Worked example, step by step
Suppose a radar transmits a pulse with width τ = 2.5 µs. Step 1: Convert the pulse width to seconds: τ = 2.5 × 10^-6 s Step 2: Use c = 3.0 × 10^8 m/s Step 3: Substitute into the formula: ΔR = cτ / 2 Step 4: ΔR = (3.0 × 10^8 × 2.5 × 10^-6) / 2 Step 5: ΔR = 750 / 2 = 375 m Final answer: the radar range resolution is 375 m.
Common mistakes to avoid
- Forgetting to convert microseconds or nanoseconds into seconds before calculating
- Omitting the division by 2, which would double the predicted resolution distance
- Confusing range resolution with maximum range or radar accuracy
Did You Know?
To resolve closely spaced targets radars use very short pulses — or pulse-compression chirps — so a long-range radar can still separate objects only metres apart.
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