How does low observable or stealth technology affect the radar cross section of an aircraft?

Low observable (LO) or stealth technology reduces the radar cross section (RCS) of an aircraft by combining geometric shaping and radar absorbing materials (RAM) to minimize the electromagnetic energy reflected back toward a threat radar. Shaping is the primary RCS reduction technique, using flat, faceted surfaces (F-117) or smooth curved shapes (B-2, F-22, F-35) that redirect incident radar energy away from the radar rather than back toward it. The key shaping principles include aligning all major edges and surface discontinuities to a few specific angular directions (planform alignment) so that strong reflections occur only at predictable, manageable angles, eliminating right-angle structures (dihedral and trihedral corner reflectors) that create strong specular returns at many aspect angles, and blending surface transitions smoothly to avoid diffraction and surface wave scattering. RAM coatings absorb a portion of the incident radar energy and convert it to heat, typically providing 10-20 dB of RCS reduction at the design frequency. The combination of shaping and RAM can reduce an aircraft's RCS from 10-100 square meters (conventional fighter) to 0.001-0.01 square meters (stealth fighter), a reduction of 30-40 dB that dramatically reduces radar detection range.