3.1 Scan Pattern

The radar antenna forms a directional beam that is 4.8° wide when the half-power points are plotted for its transmission wavelength (about 3 cm). The antenna continously rotates this beam in a 4.2° circle around its longitudinal axis. This rotating beam pattern (known as a conical scan) covers a circular area 9° wide. The received signal remains balanced while the target remains centered in the scan pattern. If a target moves away from the center, the received signal becomes unbalanced. This unbalanced signal is used to steer the antenna's longitudinal axis back on the target, thus automatically following (tracking) the target.

In search mode, the antenna's longitudinal axis is swept side to side at certain elevations. The 3-bar scan pattern with upper, middle, and lower bars covers a rectangular area in front of the aircraft that is 60° wide and 24° tall. The scan pattern is relatively complex as illustrated in the diagram.