14190_46

1-34 Figure 1-24.—Surface-search radar. Q32. What type of radar provides continuous range, bearing, and elevation data on an object? Q33. Radar altimeters use what type of transmission signal? Q34. A surface-search radar normally scans how many degrees of azimuth? Q35. What limits the maximum range of a surface-search radar? Q36. What is the shape of the beam of a surface-search radar? Air-Search Radar Air-search radar systems initially detect and determine the position, course, and speed of air targets in a relatively large area. The maximum range of air-search radar can exceed 300 miles, and the bearing coverage is a complete 360-degree circle. Air-search radar systems are usually divided into two categories, based on the amount of position information supplied. As mentioned earlier in this chapter, radar sets that provide only range and bearing information are referred to as two-dimensional, or 2D, radars. Radar sets that supply range, bearing, and height are called three-dimensional, or 3D, radars. (3D radar will be covered in the next section.) The coverage pattern of a typical 2D radar system is illustrated in figure 1-25. A typical 2D air-search radar antenna is shown in figure 1-26. Figure 1-25.—2D radar coverage pattern.