Avionics EMC
Comparison
| Parameter | Typical | High-Perf | Unit | Notes |
|---|---|---|---|---|
| Frequency | Standard | Extended | GHz | Band-dependent |
| Performance | Nominal | Optimized | dB | Application-specific |
| Linearity | Moderate | High | dBc | System requirement |
| Integration | Discrete | Monolithic | — | Cost vs performance |
| Cost | Low | Premium | $ | Volume-dependent |
Understanding Avionics EMC
Frequently Asked Questions
How does avionics EMC differ from automotive EMC?
Avionics EMC is more severe in three ways: lightning strike currents (200 kA vs. not applicable in automotive), HIRF exposure from airport surveillance radar (7400 V/m vs. 200 V/m automotive), and altitude derating (reduced cooling and increased arcing risk at 40,000 feet). But automotive has harsher temperature requirements (-40 to +150C vs. -55 to +70C for most avionics).
What is HIRF?
High Intensity Radiated Fields. Aircraft routinely fly through radar beams from airport surveillance radars (ASR-9 at 2.8 GHz, 1.3 MW peak power) and military radars. The resulting field strengths can exceed 7000 V/m. DO-160 Section 20 Category Y tests avionics at these extreme levels.
Why is lightning a major EMC concern for aircraft?
A lightning strike injects 200,000 amperes into the aircraft skin, creating massive magnetic fields and voltage differentials between different parts of the airframe. Current flows through the skin (fuselage acts as a Faraday cage) but couples into wiring harnesses through apertures (windows, seams, antenna holes). Every avionics box must survive these induced transients per DO-160 Section 22.