When the relative motion is causing the object and the RADAR to move apart, how will the reflected signal's frequency compare to the transmitted signal?

When the relative motion between the object and the RADAR causes them to move apart, the frequency of the reflected signal will be lower than that of the transmitted signal. This phenomenon is due to the Doppler effect, which describes how the frequency of a wave changes in relation to an observer moving relative to the source of the wave.

In the case of RADAR systems, as the object moves away from the RADAR, the sound or electromagnetic waves emitted by the RADAR are stretched, resulting in a lower frequency of the reflected signal when it returns to the RADAR. This shift to a lower frequency signifies that the object is moving away, allowing the RADAR system to determine the velocity of the target based on this frequency change.

Understanding this principle is crucial in the operation and interpretation of RADAR data, as it forms the basis for detecting relative motion and calculating speed accurately.