Avtomatika L-112E anti-radiation seeker. This family of seekers employs a characteristic gimballed multiple baseline interferometer design which uses a cluster of seven wideband hemispherical spiral antennas, providing for pitch/yaw steering outputs and ambiguity resolution in both axes. The design is a credible candidate for larger SAM airframes such as the 48N6E series and 5V28 series (© 2009 Vitaliy V. Kuzmin).

The installation of anti-radiation seekers in SAM airframes is not a new idea. The PLA's FT-2000 anti-radiation SAM was built with a wideband anti-radiation seeker. Narrowband Home-On-Jam (HOJ) capability has been installed in a range of semi-active and active homing radar missile seekers, primarily intended to discourage active jamming of the missile seeker. The MIM-104B ASOJ Patriot variant is credited with such a capability.

There are no open source reports of dedicated anti-radiation seekers being installed in recent Russian SAM designs. A narrowband passive anti-radiation capability is likely in more recent semi-active and TVM capable seekers, as this capability exists in supersonic anti-shipping missile active radar seekers of similar size.

There are no fundamental technical obstacles to the retrofit of a wideband anti-radiation seeker to larger Russian SAM airframes, such as the 48N6, 9M82, 9M83 or legacy 5V28. Existing seekers such as the Avtomatika L-111E/112E/113E series used in subtypes of the Kh-31 / AS-17 Krypton anti-radiation missile are geometrically and volumetrically compatible with these SAM airframes. Guidance adaptations would not be particularly challenging where the missile employs midcourse command link / inertial guidance, the principal aim being to fly the missile into a viable acquisition basket for the seeker, and cue the seeker to acquire the intended emitter. Modern anti-radiation missile seekers are usually capable of autonomous target acquisition, or re-acquisition should an emitter go silent transiently.The technology is certainly available to inexpensively equip any number of recent Russian SAM airframes with anti-radiation seekers. Passive targeting capability via emitter locating systems such as the 85V6 Vega / Orion or Kvant 1L222 Avtobaza presents no difficulty, both designs have been integrated with the S-400 / SA-21 fire control system. The CONOPS for such a system would involved passive angle tracking and ranging on an emitter, with the SAM round flown out under command link control to a geometrically optimal position, upon which the anti-radiation seeker would acquire the target and terminal homing would be performed. Existing control laws for terminal homing in HOJ modes would be viable.

Until terminal homing is initiated, a defending aircraft will have no easy means of determining whether an inbound SAM is fitted with an anti-radiation seeker. This will complicate defensive countermeasures scheduling and defensive tactics. A salvo of two SAMs, one with an anti-radiation seeker, and one with an active or semi-active homing seeker, will present similar difficulties to those seen with the use of mixed seeker types in Beyond Visual Range (BVR) AAM attacks.