The effect of radome-induced sight line errors on radar tracking accuracy

Airborne surveillance, fire-control and homing missile radars are enclosed within a protective radome. Such radomes cause distortion of the propagating wave front, manifest as an aberration of the antenna boresight. In addition to the direct effect on radar measurement accuracy, non-uniformity of the aberration error is capable of inducing significant errors in the estimated sightline-rate: this can degrade radar fire-control performance in tactical aircraft, and is known also to be a potential cause of steering-loop instability in radar-homing missiles. Therefore, when analysing tracking performance for such systems it is important to quantify radome-induced errors and so establish the need, or otherwise, for correction of the sightline data. The purpose of the paper is to show how computer simulation and theoretical analysis may be used in combination to obtain a full characterisation of the target-tracking errors to which radome aberration gives rise, for the important special case of precision Kalman filter, lock-follow tracking in an agile tactical aircraft