Introduction#

Radar sensors determine distance by emitting electromagnetic waves and evaluating their echoes. The BRS0002 uses FMCW (Frequency Modulated Continuous Wave).

In FMCW operation the sensor continuously changes its transmit frequency in rising and falling ramps ("chirps"). When the signal hits an object, the echo returns time‑shifted. All reflected echoes form a spectrum. The peaks in this spectrum can be converted into a distance.

The magnitude of a peak describes the strength of the received echo. It is influenced by material properties (conductive / dielectric), size and orientation of the surface, surface texture (smooth vs. rough), distance (two‑way attenuation), angle as well as shadowing or multi‑path. Magnitude is relative – comparisons under identical conditions are more meaningful than individual values.

Materials: Metals reflect strongly. Dry non‑conductive materials (e.g. some plastics, wood) allow part of the energy to pass; objects behind can be visible provided their echo is not masked. Moist or water‑containing substances attenuate more strongly and reduce visibility of targets behind. “Penetration” means: An attenuated portion passes through – not full “see‑through”. More information on reflection properties is in the Manual.

Geometry: Frontally aligned, flat surfaces deliver strong peaks. Angled or strongly curved surfaces deflect energy away – the echo is weaker. Round or cylindrical shapes scatter; edges or corners can locally amplify.

Each peak is the interplay of material, shape, angle and distance. Changes over time or differences between defined states provide the greatest information gain.