CR40
42
/50 MKII Radar operation
Chapter 7
87
a fixed relationship with respect to the true image and characteristically
produces a more arc-like appearance with a tendency to smear on the
screen. Ghost images are sometimes caused by large targets which
have a wide, smooth surface as they pass by near your own ship.
Ghost images sometimes are referred to as indirect echoes. Indirect
echoes may appear when there is a large target, such as a passing ship
at a short range, or a reflecting surface, such as a funnel or spotlight on
your own ship in line with the antenna. The signal, on first striking the
smooth side of the large target, will be reflected, and these subsequent
echo returns to the antenna are shown on the display. However, the
same reflection may also hit other masts or obstacles and then be
picked up by the radar antenna with enough strength to appear as a
target on the radar screen at various locations.
Multiple echoes could appear if there is a large target having a wide
vertical surface to your own ship at a comparatively short range. The
transmitted signal will be reflected back and forth between the wide
vertical surface of the target and your own ship.
Thus, multiple echoes will appear beyond the true target’s echo on the
same bearing as shown below. This is not a very common phenomena.
True echo
Multiple
echoes