Which type of mode does not experience the Doppler shift when radar is stationary?

The correct answer is based on the principle that the Doppler shift in radar systems occurs due to relative motion between the radar and the target. In stationary mode, the radar is not moving; therefore, there is no change in frequency of the returned signal caused by motion. The Doppler effect relies on the speed of the target relative to the observer. When the radar is stationary and there are no moving targets, there is no change in frequency or waveform of the radar signal.

In contrast, moving mode would involve scenarios where the radar itself is moving or the targets are moving relative to the radar, both of which would contribute to a Doppler shift. Static targeting does involve stationary targeting, but it implies that the target can still be moving relative to the radar. Multi-target mode allows simultaneous tracking of several targets, which could also be in motion, leading to Doppler shifts. Hence, stationary mode is the only mode where the radar does not experience any Doppler shift when it is stationary.