§11.10 Stealth

Stealth (signature reduction, low observability) is the quietest form of ECM: no jamming, no deception, but making sure that the sensor receives too little signal to detect anything at all. It attacks the energy balance itself — the radar equation of Inverse square law.

The techniques per signature:

• Radar (RCS, Radar Cross Section):
  • Shaping — the lion's share: flat, angled panels and aligned edges deflect the energy away from the radar instead of back (a conventional aircraft has corners everywhere that act as reflectors); no right angles, shielded engine inlets, internal weapons bays.
  • Materials — for whatever shaping cannot get rid of. There are two forms, and the difference matters:
    • RAM (Radar Absorbent Material): radar-absorbent material applied as a layer on the surface — coatings, paints and bonded panels (e.g. with carbonyl iron or graphite) that convert the RF energy into heat in a thin, lossy layer. Effective, but it adds weight, wears under weather and use, and requires intensive maintenance — the notorious "stealth maintenance burden".
    • RAS (Radar Absorbent Structure): here the absorbing function is built into the load-bearing structure itself — usually composite layers (a honeycomb or laminate structure with lossy materials) that carry loads and absorb radar at the same time. RAS is lighter and more durable than an applied layer and is "designed in" to the airframe, but it has to be included from the design stage and cannot be retrofitted.
    The difference in one sentence: RAM is a layer applied on the structure; RAS is absorption integrated into the structure. Both convert radar energy into heat — modern aircraft rely increasingly on RAS to limit the maintenance burden of RAM.
  • Detail discipline: panels, seams, antennas and even screw heads are potential reflectors; stealth is also a maintenance regime.
• IR (Infrared): mixing exhaust jets with cold outside air, shielded/flat nozzles, fuel as a heat sink, low-IR paint — against IRSTs and heat seekers.
• Emissions (EMCON): the platform's own radar and data links are give-aways (Electronic Support Measures); stealth platforms work passively as much as possible, with LPI waveforms (Frequency Modulated Continuous Wave radar) and strict emission discipline.
• Visual/acoustic: colour schemes, avoiding contrails, low-noise profiles.

What stealth does and does not do follows from the fourth root (Inverse square law): reducing the RCS from 5 m² to 0.0005 m² (a factor of 10,000) shortens the detection range "only" by a factor of 10. Stealth makes you invisible at range, not invulnerable up close. The aim is to shrink the opponent's detection and engagement rings so much that gaps appear to plan through — stealth is a mission-planning instrument, not a cloak of invisibility.