Beam steering unit real time angular monitor

Proper operation of a beam steering unit for a phased array antenna, is verified by simulating the pattern of wave energy which would be radiated to an observation point in space. The simulated pattern may be compared with a preset pattern during a scanning operation of the beam steering unit, and an alarm or other indication is obtained when the difference between the simulated and the preset pattern exceeds a certain limit. The simulated pattern is obtained by storing phase angle data from the beam steering unit in a memory at areas corresponding to phase shifters associated with elements of the phased array antenna. The memory areas are incremented from initial phase angle data corresponding to the beginning of a scan operation, in accordance with phase angle data provided by the beam steering unit at certain time intervals. Observation angle data corresponding to the angle of the point in space relative to the antenna array is generated (via 30, 32). The updated phase angle data is combined (via 34) at each time interval with the observation angle data. From this angle data is subtracted (36, 40) the angle data for the immediately preceding time interval, and the resulting differences are accumulated (38, 42) with initial value angle data to produce a running accumulation (44) of angle data in real time. The relative amplitude of wave energy which would be observed at the point in space during a scanning operation of the beam steering unit is then determined (via 46) as a function of the accumulated angle data in real time.