Radar Range Calculator
Compute maximum detection range, received SNR, and minimum detectable signal using the monostatic radar range equation. Includes range vs power chart and full link budget breakdown.
| Parameter | Value | Notes |
|---|
| Target | Typical RCS σ | dBsm | Notes |
|---|---|---|---|
| 🐦 Bird / small UAV | 0.0001 m² | −40 dBsm | Very low RCS target |
| 🛸 Small drone (DJI-size) | 0.01 m² | −20 dBsm | Counter-UAS challenge |
| 🚶 Person (walking) | 0.05–0.5 m² | −13 to −3 dBsm | Depends on aspect angle |
| 🏎 Small car | 1 m² | 0 dBsm | Side aspect |
| 🚗 Car / SUV (front) | 10 m² | +10 dBsm | Front/rear aspect |
| 🛩 Small aircraft (GA) | 0.5–2 m² | −3 to +3 dBsm | General aviation |
| ✈️ Commercial aircraft | 10–100 m² | +10 to +20 dBsm | Broadside aspect |
| 🥷 Stealth aircraft (F-22) | ~0.001 m² | −30 dBsm | Classified, approximate |
| 🚢 Large ship | 1000–100000 m² | +30 to +50 dBsm | Depends on aspect |
| 🛥 Small boat | 100 m² | +20 dBsm | Typical for marine radar |
| 🚁 Helicopter | 0.3–3 m² | −5 to +5 dBsm | Rotating blades modulate |
| 🚂 Train (broadside) | ~400 m² | +26 dBsm | Large metallic structure |
About the Radar Range Calculator
This calculator implements the monostatic radar range equation — the fundamental formula that determines how far a radar system can detect a target of given radar cross section (RCS). It accounts for transmit power, antenna gain, wavelength, target RCS, noise figure, required SNR, and system losses.
The Radar Range Equation
The received power from a target at range R in a monostatic radar (same antenna for TX and RX) is:
Solving for maximum range Rmax:
Rmax = [ Pt · G² · λ² · σ · n / ((4π)³ · k·T₀·B·NF · SNRmin · L) ]^(1/4)
where k = 1.38×10⁻²³ J/K (Boltzmann), T₀ = 290 K, B = 1/τ (matched filter), n = pulses integrated
Key Parameters
Radar Cross Section (RCS, σ) — the effective "mirror area" of the target. A larger RCS means more signal bounces back to the radar. RCS depends on target size, shape, material, and the aspect angle. Stealth aircraft use shaping and radar-absorbent material (RAM) to minimise RCS.
System Losses (L) — includes atmospheric absorption, radome insertion loss, waveguide losses, mismatch losses, and signal processing losses. A typical value for X-band radar is 4–10 dB total.
Pulse Integration (n) — coherently integrating n pulses improves SNR by n times (10·log₁₀(n) dB). Non-coherent integration improves SNR by approximately √n. This calculator assumes coherent integration.
The R⁴ Dependence
Notice the range appears as R⁴ in the denominator — this is the crucial difference between radar and one-way communication. The signal travels to the target (R² loss) and back (another R² loss). This means doubling the transmit power only increases range by 19% (2^(1/4) = 1.189). To double the radar range, you need 16× more transmit power — which is why radar engineers obsess over every dB.
Minimum Detectable Signal (MDS)
The MDS is the weakest signal the radar receiver can distinguish from noise. It equals the thermal noise floor raised by the noise figure and the required SNR: MDS = k·T₀·B·NF·SNRmin·L. Any received signal below MDS will be buried in noise and undetectable.