[svandamme]

Smells like boooolsjiiit to me.

"The Only picture available"
That picture could be anything, theres no telling if that is even an F117

Furthermore the idea of detecting radar on a stealth plane,
doing that by breaking the stealth design and flipping out a square detector box, which would increase the RCS and make the plane easier to show up to the radar.

is just a big "does not compute" to me.

I doubt they cared all that much, since the F117 was mostly designed to defeat Fire control (lockon) radars, not general Early Warning Radar..
The enemy usually would have a general idea that "somethign" was up there, but they simply could not lock on to it.
Lock on radar has completely different band and wavelength

The EWR locations on the really dangerous sam sites are generally in known locations, Satelite and U2's would have already figured all of that out prior to attacking.

The F117's would then optimize their flight, ingress and egress to avoid bad angles vs such big radars... (pule radar only detects changing distance to the radar, if you fly perpendicular it detects nothing)

And the regular RHAW gear does not use antennas that look like that RLS at all,
they are very simple systems that don't need much antenna to detect the powerful big radars..