Checking out the Zhuk-M1E radar at Aero-India - the new unit developed by Phazotron for the MiG-29M, MiG-29K and upgrades - one detail was obvious: the backside of the radome and the front of the bulkhead were covered with what looked like something you'd clean the barbecue with.
Photo by Bill Sweetman
It's radar-absorbent material (RAM) and pretty effective RAM at that. Nothing very exotic, but it does not need to be, since it is sealed up inside the radome and protected from aerodynamic forces, heat and moisture. In fact, US RAM specialists Emerson & Cuming sell a very similar product on the open market, an open-cell plastic foam doped with carbon absorber.
Russians are not stupid and do not do things if there is no point, and there would not be a lot of point in dealing with the radar-cross section (RCS) hotspot from the radar antenna if they had not also dealt with the other sore-thumb hotspots, namely the inlets/compressor faces and the cockpit.
The technology to do this was described in detail in technical papers delivered in London some years ago by representatives from the ITAE research institute, who had applied it to the Su-27 family. ITAE had even worked out how to apply RAM directly to the first-stage fan blades, which is quite a neat trick, and had devised spray-on RAM for missiles. One may assume these or similar measures are available to MiG.
The same kind of measures are also used on many Western aircraft, but are usually not shown in detail unless someone screws up:
Whoops. That's a Have Glass II F-16 and the white plastic shroud around the radar workings is RAM.
Reducing the front-sector RCS, mostly in X-band, is a far cry from full-up stealth technology. It does not make the aircraft invisible. But what it does do (and quite effectively) is make jamming more effective by reducing the burn-through range (the point at which a radar defeats jamming because the reflection is stronger than the jamming signal).
The lesson: Any combat-effectiveness comparisons that are based on the old standard for the nose-on RCS of a fighter - around 5 m2 - can be considered invalid.