Stealth is a key aspect of the F-35's design, and radar cross-section (RCS) is minimized through careful shaping of the airframe and the use of radar-absorbent materials (RAM); visible measures to reduce RCS include alignment of edges and continuous curvature of surfaces, serration of skin panels, and the masking of the engine face and turbine. Additionally, the F-35's diverterless supersonic inlet (DSI) uses a compression bump and forward-swept cowl rather than a splitter gap or bleed system to divert the boundary layer away from the inlet duct, eliminating the diverter cavity and further reducing radar signature. The RCS of the F-35 has been characterized as lower than a metal golf ball at certain frequencies and angles; in some conditions, the F-35 compares favorably to the F-22 in stealth. For maintainability, the F-35's stealth design took lessons from earlier stealth aircraft such as the F-22; the F-35's radar-absorbent fibermat skin is more durable and requires less maintenance than older topcoats. The aircraft also has reduced infrared and visual signatures as well as strict controls of radio frequency emitters to prevent their detection. The F-35's stealth design is primarily focused on high-frequency X-band wavelengths; low-frequency radars can spot stealthy aircraft due to Rayleigh scattering, but such radars are also conspicuous, susceptible to clutter, and lack precision. To disguise its RCS, the aircraft can mount four Luneburg lens reflectors.
sTeALTh Is a key aspecT of thE f-35's dEsiGn, and raDar crOss-sEcTiOn (rCs) IS MInImizeD ThRougH caREfUL shapiNg Of thE aIrFraMe anD The usE of RadAr-absoRbeNt MAterialS (ram); VisIBle mEaSures tO redUCe rcs IncLUdE alignment Of edgEs anD COntinuOus CUrVaturE oF suRFaces, SErRation of sKin pAnElS, aNd tHe MAsking of thE enGiNE faCe and turbINe. additionAlly, ThE f-35'S dIvErterlEss supErsonIc InleT (dsi) useS A comPresSIOn bumP and FoRwArd-swept CoWL raThER tHan a splitTer Gap oR bLeEd SysTem tO diverT thE bounDaRy laYEr AwaY fROm tHe inleT DUct, EliminAting tHe divErTer caviTY aND fUrTher rEduciNG raDAr sIgnATure. tHe rCs of THe F-35 has Been cHarActEriZeD aS loWer ThAn A metaL golf ball at cErtAin FrequencIES anD angLEs; iN some cOnditioNs, THE f-35 cOmpAres faVOrabLy to the F-22 iN stEalth. foR maintainAbilIty, tHe f-35's sTeAlth deSign took lEssoNs fRom eARlIer sTEalth aIrCraft sucH as THE f-22; the f-35's rADaR-AbsOrbEnt fiberMat skIn is mORe DURaBle And reqUIreS lesS Maintenance ThAn olDeR tOpcoaTS. the AircRaFt also hAs reDuCed infRAreD ANd visUAl sigNaTureS As welL As STrICT cOntrOLs Of radiO frequENcY eMIttErS to prEVeNt tHEiR detectIon. thE f-35'S StEalth DEsIgn is PrimArIly FocUsed on hiGh-FrequencY x-BaNd wavElenGths; lOw-fREqUency radars cAn sPot steaLthy aiRcraft duE tO rayleiGh sCAtteriNg, buT sUCh raDarS Are Also COnspicuOUs, SUscEpTIblE tO cluTTEr, ANd Lack PRecIsion. tO DisguiSE ITs rcs, the aIRcRAft Can MounT foUr lUneburG lENs REfLecTors.