THE DESIGN BRIEF

Bulk Cable Injection (CS114) failures continue plaguing defense contractors at 10 kHz–200 MHz on interconnecting cables. The standard requires equipment survival under 1V RMS continuous wave injection, but many designs fail catastrophically at 27 MHz and 108 MHz due to inadequate common-mode filtering.

Critical design threshold: maintain >40 dB common-mode rejection at frequencies above 10 MHz. For cables exceeding 3 meters, implement ferrite cores with impedance ≥300 Ω at problematic frequencies. The Damped Oscillatory Transients test (CS116) at 10 kHz–100 MHz compounds this issue—designers must ensure power supply ripple rejection exceeds 60 dB across this band to prevent CS116 coupling through inadequately filtered DC rails.

• • CS101 conducted susceptibility now catching DC-DC converters with less than 50 dB PSRR below 150 kHz—specify minimum 70 dB rejection at 30 Hz–10 kHz
• • RE102 radiated emissions failures cluster at 108 MHz and 225 MHz due to cable resonances—keep harness lengths away from λ/2 multiples
• • RS101 magnetic field testing at 30 Hz–100 kHz requires H-field immunity >140 dBμA/m for sensitive analog circuits
• • CISPR 16-1 measurement apparatus updates specify 3-meter semi-anechoic chamber correlation within ±4 dB of open area test sites