3.1.1 Range profile signature

In this chapter high-range resolution radar is presented. A high-resolution range profile (HRRP) is a one-dimensional signature of an object. It is a representation of the time domain response of the target to a high-range resolution radar pulse. An example of the range profile of an aircraft in flight is provided in Figure 3.1. In each high-resolution range cell the amplitude of the signal is measured giving the strength of the return at that time delay. The main parts of the aircraft which contribute to the range profile are shown. It should be noted that most targets do not appear to have the same radar length as their physical length due to two effects. Rather than the signal being reflected back towards the radar directly, it can bounce between different scatterers comprising the target, so the time delay is increased, which is manifested in the radar range profile signature being longer than the target. The other effect, which can occur, is the shadowing of one part of the target by another part. This occurs when part of the target is obscured by a large part of the same target located between it and the radar, significantly reducing the energy in the wave reaching it and being reflected back to the radar. When this occurs at a particular aspect angle, a certain part of the target may not contribute to the range profile. For example, the fuselage and wings of a civil airliner can obscure...