Faceting and curves
The F-117 used flat facets because 1970s computers couldn't simulate curved surfaces. The B-2 and F-22 use carefully shaped curves because better software solved the equations. Both achieve the same goal: no surface returns energy back toward the threat radar. Faces angle to deflect reflections sideways and upward, away from ground-based threats.
Edge alignment
Every straight edge on a stealth aircraft is aligned with one of a small number of master angles — typically the leading-edge sweep. This concentrates the edge diffraction into narrow beams pointing in known directions, leaving most of the sphere RCS-free. Wing tips, weapon bay doors, panel seams and antenna covers all follow the same angles.
Radar-absorbent materials
RAM coatings convert incoming microwave energy into heat through resistive losses. Modern RAM is a layered composite tuned to the threat band, applied centimetres thick on key surfaces. The maintenance cost is brutal — a B-2 needs hours of RAM repair after every flight.
Frequency dependence
Stealth is band-specific. F-22 and F-35 are optimised against X-band fire-control radars. Long-wavelength VHF radars (the Russian Nebo-M series) can detect them at much longer ranges because the wavelength is comparable to airframe features — they resonate. This is why low-frequency surveillance radars are seeing a revival.