Douglas Barrie/LONDON

The US Air Force is developing a secondary passive anti-radiation seeker for the Raytheon AIM-120 Advanced Medium Range Air-to-Air Missile (AMRAAM).

The Passive Adjunct Seeker Antenna project is led by the USAF's Wright Laboratories Armament Directorate. A demonstration of the passive seeker antenna has already been carried out, says the USAF research organisation.

A passive adjunct seeker would provide the AMRAAM with a dual-mode capability. At present, the AIM-120 relies on its active radar seeker for final target acquisition and terminal guidance.

A secondary seeker would allow for the passively guided launch of an AIM-120 against a target aircraft when the latter's air-intercept radar is emitting. Such an engagement would not require the launch aircraft to use its own radar, with the AMRAAM's passive seeker homing on the radio frequency energy from the target radar. Were the target aircraft's radar to be turned off, then the AMRAAM could revert to the active seeker to relocate it.

Russian missile design house Vympel has developed a passive homing version of the R-27 (AA-10 Alamo) missile, the R-27P, which is in service with the Russian air force. US sources suggest that the USA Fmay have already developed, and fielded, a passive seeker-only version of the AIM-120.

The passive adjunct seeker is one of several Wright-led developments intended to improve the AIM-120. Other areas of work include developing a "multi-mode seeker with enhanced processor hardware and algorithms to improve the target identification capability and end-game accuracy," says the USAF laboratory.

Source: Flight International