[Terp]

The nature of the target emitting radar signature would be very different as well from that expected for a ship.

Not true, we used to joke if we knew a Sunburn was fired at us that we would have the ships helo go out behind us with it's navigation radar on and we onboard the ship would turn our radars off and the missile would take out the helo.

Terp

[Mark Felton]

More sophisticated US radar seekers would not likely be as easily fooled, and I suspect the same is true for the Sunburn (it's fairly new Chinese/Russian technology).

If the Sunburn gets an initial lock it would use both the IR and radar trackers together to confirm and maintain lock. In the event that the the radar signature went away then it would use the IR tracker. Both trackers will maintain "quality" scores and the chosen tracker will have the highest score.

Rapid spatial changes in one tracker but not the other would be filtered out because it would present a lower "qaulity" value and be inconsistent with expected target dynamics. So that poor track would be ignored.

Your helicopter spoofer might help but it would be a slow response, and an incomplete response. The missile is supersonic, and the IR signature would also have to be spoofed simultaneously.

Sea-skimming missiles are notoriously one of the most difficult missiles to counter.