The Physics of Stealth: Why Airframes Cannot Simply "Absorb" Low-Frequency Radar
Salisbury Screen Resonant Cancellation: Radar Absorbent Material (RAM) is not magic paint; it is an electromagnetic impedance-matching layer. Incident radar energy partially reflects from the outer dielectric boundary and partially penetrates to the conductive aircraft structure. When coating thickness equals one-quarter of the wave's internal wavelength (d = λ / 4√ε_r), the wave reflecting from the airframe travels an exact half-wavelength round trip (λ/2 = 180° phase shift). It emerges in destructive opposition to the front surface reflection, converting radio frequency energy into thermal dissipation.
The Low-Frequency Detection vs. Fire-Control Paradox: As discussed in defense analysis, long-wavelength radar (VHF/UHF, λ = 0.6m to 2m) overcomes shaping because the aircraft's control surfaces (tail fins, wingtips) fall within the Rayleigh/Mie resonant scattering regime. While early warning VHF radars easily spot stealth fighters at 100+ miles, their huge wavelength prevents them from generating the sub-meter precision tracking required for active missile radar seekers (which operate in X/Ku-band). Defeating VHF with RAM would require a 1-foot thick layer adding over 10,000 kg—rendering the jet aerodynamically incapable of flight.