The focus in Russian CVLO radar has been in the 1-meter VHF band. Stealth shaping in fighters is largely ineffective in VHF because components such as stabilizers and wingtips have dimensions close to the radar wavelength. Radar-absorbent treatments developed for S-band and above are ineffective in VHF due to both electrical behavior and thickness.
The flagship product is the NNIIRT/Almaz-Antey 55Zh6M Nebo M 3-D radar system, of which 100 were recently ordered to re-equip Russian air defense forces. The Nebo M is uniquely a “multi-band” design, comprising three radars and a central data fusion and command post module, all carried on separate high-mobility 8 x 8 24-ton vehicles.
The RLM-M VHF-band, RLM-D L-band and RLM-S C/X-band radars all feed tracking data to the command van's data fusion system—which resembles the U.S. Navy's Cooperative Engagement Capability system—using high-speed narrow-beam digital data links in the microwave band. All radars appear to be solid-state active, electronically scanned array (AESA) designs. The intent of the Nebo M design is for the RLM-M to detect stealth targets, and cue the RLM-D and -S components to produce exact tracking data, bypassing the initial acquisition problems otherwise seen in mid/upper-band radars with VLO targets. Range performance has not been disclosed but the RLM-M is expected to better the earlier Nebo- SVU by at least 40%.
The earlier NNIIRT 1L119E Nebo-SVU VHF AESA does not appear to have been built in large numbers, and used a less mobile semi-trailer configuration. The Nebo-SVU was credited with space-time adaptive processing technology similar to that or the
Northrop Grumman E-2D Hawkeye, and in 2002 NNIIRT's Igor Krylov said
“We can see the stealth [F-117A] as clearly as any other plane”.