This technology is one of the most closely guarded secrets of the Russian Airforce and details are not published yet. However I found this article and re-produce it below. They say that it is or will be far better than the US Lockheed Skunk Works or Northrop versions. An exclusive interview about these technologies was conducted by Nicolai Novichkov, ITAR-TASS with director of the Center, academic of Russian Scientific Academy Anatoliy Korteev. The main drawbacks of the Stealth technology are its negative effects on the flight and agility characteristics of the stealth aircrafts.
Russian scientists approach the issue from the other direction.
They proposed to create a plasma formation around protected object, which prevents radars from seeing it. Thus, aerodynamical characteristics of the plane itself do not suffer. Without interfereing with technical characteristics the artificially created plasma cloud surrounding the plane guarantees more than hundred times decrease in its observability. The physics of plasma protection can be described as following. If an object is surrounded by a cloud of plasma, several phenomenas are observed when the cloud interacts with electromagnetic waves radiated by enemy radar.