What I want to know is how do the justify their claims that it can shoot down a stealth plane? Sounds like a lot of hooey to me.
A stealth aircraft differs from a non-stealth aircraft in three primary ways.
The first method is to diminish the heat radiation coming from the aircraft in order to eliminate or greatly reduce the heat signature to defend against Infrared seekers.
The second method is to shape the aircraft in a manner that will not reflect the radar energy back to the receiver back at the radar site. Most aircraft these days incorporate a limited degree of shaping for this purpose, some even retroactively.
The third method is to coat the aircraft with radar absorbent material. The reason for absorbing the radar energy is that in an advanced air defense system, the radar sites are integrated and situated in a manner as to make it possible to use multiple radar sites to triangulate the position of enemy aircraft. Therefor, even though radar energy may be reflected, it may only be reflected to another radar site.
All of these factors taken together give a given aircraft what is called a radar cross section. All aircraft have a radar cross section, including the venerable B-2 and the newer F-22, but also birds. Most current radar systems cannot detect or differentiate between the radar cross section of a bird or the F-117. Aircraft like the B-2, the F-22, and possibly the F-35, have a radar cross section smaller than that of a bird.
The radar cross sections of the various popular stealth aircraft varies from one source to another, but most agree that the the RCS of the B-2 is about the size of an aluminum marble, with the F-22 being very similar. The F-35 is expected to have an RCS of anywhere between that of golf ball to a basketball. The F-117 is said to be similar in that regard.
What advanced radar systems are doing today is utilizing computer technology to pick up all signals in the air, including birds, allowing the computer to differentiate between birds and man-made low-observable objects and then put those "blips" on the screen that it thinks are enemy objects, such as missiles or aircraft. Until recently, this was impossible. There just did not exist the computing power to sort through all of those signals and report back the needles in the haystack that were stealth aircraft.