MR-231

The MR-231 "Najada" (water nymph) is a family of X-band naval navigation radars designed for vessels with a gross tonnage exceeding 10,000 tonnes, operating at a frequency of 9,410 ± 30 MHz. These radars primarily differ in their antenna configurations. The MR-231-1 "Pal" (Dolphin structure) utilizes two antenna lengths, 1.6 m and 3 m, both with waveguide feeds, and features an external, more powerful rotary motor due to antenna size. The MR-231-2 "Liman" (backwater) employs a 1.495 m waveguide slot antenna with an internal motor; a civil variant, Liman 18M1, differs primarily in external color. The MR-231-3 "Vajgatch" (name of a Russian North Sea island) uses a reflector antenna and has a peak power of 25 kW. The MR-231-4 "Gals" (sailing maneuver) features an antenna enclosed within a small cylindrical radome and has a lower peak power of 4 kW. All variants share common specifications including pulse repetition frequencies of 2.8, 1.4, or 0.7 kHz, pulsewidths of 0.06, 0.35, or 0.8 µs, an instrumented range of 48 nautical miles (89 km), and an antenna rotation speed of 15 revolutions per minute.

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