Communications, Radar & Electronic Warfare (201.. - Index of

Radar and Radar Jamming 121shows the previous scan, including returns from targets and clutter. The middle imageshows the successive sweep, which contains much the same data as the first one. Byretaining the original scan in memory and then removing the duplicates, the three targetscan be clearly differentiated from the clutter as illustrated in the right hand display.MTI radar is also used from airborne platforms. This adds a degree of complexitybecause the radar platform is moving and therefore the Doppler shift is not with respectto a speed of zero, as it would be in a fixed installation. However, with suitable computerprocessing, the effect introduced by the platform' s movement can be overcome.7.3.8 Phase Array RadarPhased array radars use sophisticated transmitter and receiver arrays composed of individualelements. The alTay face consists of a number of elements in both the horizontaland vertical directions. The instantaneous beam is formed by electlical steering usingphase delays to detennine direction; the number of elements in the horizontal plane toform the horizontal beam pattern and the number of elements in the vertical plane doinglikewise for the vertical beam pattern. This is illustrated in Figure 7.21./' / Instantaneous>- beamPhased arrayside view•••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••Front viewof arrayFigure 7.21A phased aITay radar.