64 · MT 2/2023 From the deck designed to overcome discrimination techniques featured by the most advanced missile seekers operating in the I, J and K bands. Much larger corner reflectors, instead, are available to both US and UK destroyers and frigates: the IrvinGQ DLF-3b (FDS3 or Mk59 in US service) is an inflatable offboard corner reflector launched from the ship’s deck (typically four launchers per ship), able to generate a radar cross section of 500,000 m2. This is going to be replaced (after 2025) by the Naval Passive Off-Board Decoy (N-POD) currently under development. To make a comparison, the Chinese Type-055 and Type-052D destroyers have four deck-launchers for comparable inflatable floating decoys. The other significant improvement is related to the active RF decoys. The Mk234 Nulka is an Australian-US co-development. Once launched, it starts radiating broadband RF power, receiving information from the ship’s ESM via data-link, thus generating a large ship-like radar cross section. It hovers flying a slow trajectory intended to lure anti-ship missiles away from the original target. In October 2021, L3Harris was awarded a contract to supply a series of next-generation EW payloads to equip the Mk234 Nulka active offboard decoy system, addressing new specific threats that current Nulka payloads do not. The Australian ships are fitted with a standalone “flat-pack launcher” configuration, while in the US the Mk53 Mod 4 configuration adds two Mk137 Mod 10 Nulka launching tubes to each of the existing Mk 36 Mod 12 launchers. Royal Navy’s EWCM Increment-1b calls for the procurement of a 2nd-generation RF active offboard decoy. After Accolade, a joint UK-France demonstrator for an active RF decoy, failed to be procured, in 2020 Lacroix announced VESTA (Véhicule Ejecté Support Tactique d’Autoprotection), i.e., an active decoy deployed from normal ship’s countermeasure launchers, capable to hover thanks to a rotary-wing solution. However, VESTA is expected to be operational not before 2030. The most recent member of the active decoy family is the Rafael C-GEM. It features a solid-state active array with electronic beam steering, covering distraction and seduction modes against missile seekers in the 6-18 GHz frequency band. C-GEM technology can be fitted into any decoy ammunition with caliber over 115 mm. The effect of short-range seduction chaffs launched by a Chinese 726-4 decoy launchers. (Photo: Ministry of National Defense People‘s Republic of China) It comes in different configurations, all based on the Mk 137 six-barrel launchers, ranging from two up to eight units, able to fire both mortar and rocket rounds. The Mk137 tubes are fixed at 45° elevation, while the Mk137 Mod2 tubes come in both 45° and 60° elevations. As decoy munition, the US Navy operates both the legacy Mk182 SRBOC chaffs and the Mk186 SRBOC Torch IR flares, as well as more recent solutions, such as the Chemring Mk214, Mk216 and Mk245. The US Navy’s Mk36 SRBOC configurations ranges from just twelve tubes (two Mk137 launchers), up to 48 tubes (eight Mk137 launchers), depending on the ship’s size. New challenges In the timeless fight between sword and shield, projectiles and armor, missiles and countermeasures, the appearance of more sophisticated seekers stimulated the evolution of new, more advanced, countermeasures. A first example is the need to generate a realistic signature in both IR and RF bands. This can be achieved only through combined-effect decoys or firing a mix of chaffs and flares. The Infra-Red band requires some more sophistication as well: the decoy radiation spectrum must be effective against bi-color seekers (both 3-5 μm and 8-14 μm) and must be stable and persistent enough to avoid excessive fluctuations. According to Lacroix, Sealir flares can replicate the thermal radiation of funnel and exhaust, therefore becoming effective also against IIR seekers. The millimetric-wave radar (K band) seekers require extremely small chaffs, just 2-3mm long, otherwise they would not affect the radar. While some chaff payloads now include also these very short dipoles, some smarter homing head could reject the attempt anyway, because the cloud would likely not precisely replicate a real target signal, for being too homogeneous and polarization sensitive. Lacroix promotes corner reflectors (Sealem family), as a more effective alternative to traditional chaffs. Other comparable corner reflectors compatible with multipurpose decoy launchers include the Chemring Torero 130mm ammunition with a Fast-Inflating Airborne Corner Reflector developed in cooperation with Japanese company IHI Aerospace, delivering a 10,000 m2 radar cross section thanks to a parachute. The use of such corner reflectors is The deployment of active RF decoys can greatly supplement the traditional passive decoy (chaffs and corner reflectors) solutions. Nulka, a joint US-Australian development, receives inputs from the launching ship through a data link. The US Mk53 Mod 4 configuration adds two Mk137 Mod 10 Nulka launching tubes to each of the existing Mk 36 Mod 12 SRBOC launchers. (Photo: US Navy photo by Mass Communication Specialist 2nd Class Devin M. Langer/Released) e f
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