The Performance of Semi-Active Radar Guided Missiles against Sea Skimming Targets.

The engagement of a sea skimming target by a radar-guided missile may be subject to multipath effects. That is, the radar signal reflected from the target may return to the missile seeker directly or via reflection from the sea surface giving rise to interference effects. Such interference may cause the target return signal to fade. This multipath-induced fading can cause serious missile guidance problems. In this report, a radar multipath return model is developed in MATRIXx. This model is used to evaluate the performance of a monopulse semi-active missile system against a sea skimming target. The multipath model takes into account forward scattering over a smooth sea and includes a representation of the monopulse sum and difference angle processing performed by the missile receiver. A number of parameters affect the return signal from the target. These include the height of the target above the sea surface, the radar cross-section of the target, and the sea state. Simulations were performed for a range of these parameters in order to examine their impact on the target returns and subsequently the missile performance. The simulation results, which show the adverse effects of multipath on the seeker boresight errors, are presented for typical missile-to-target engagements as a function of the parameters identified above. The multipath model described here may be used to assess the performance of particular semi-active radar homing missiles when operating over a sea surface.