What is the shape characteristic of multi-trip echoes in comparison to the original scatterer?

Multi-trip echoes result from radar waves bouncing off multiple surfaces or scatterers before returning to the radar. This phenomenon tends to elongate the echo shape because the radar system effectively observes the signal at different times as it reflects off various objects or surfaces.

When an echo is generated from a single scatterer, the shape appears more compact and representative of the original object. However, multi-trip echoes can distort this representation. The repeated reflections can create a stretching effect, making the echo appear more narrow and elongated compared to the original scatterer.

This alteration in shape arises from the geometry of the reflections; as the radar waves travel further and return after multiple reflections, the combined signals influence the appearance of the echo on the radar display. Thus, the correct answer highlights that multi-trip echoes are characterized by being more narrow or stretched relative to the original source of the signal.