1. Consideration of Electromagnetic Effects in Aircraft Design Thomas Jerse Department of Electrical and Computer Engineering Sigma Xi Brownbag Presentation 10/17/08

2. Electromagnetic Environmental Effects Safety of flight Radiation Hazards Cosite interference E3E3

3. Who Makes the Rules? FAA –DO-160 JAA Department of Defense –MIL-STD-461E –MIL-STD-464A

4. Safety of Flight Power Systems –Fly-by-wire controls 3x or 4x redundancy Air Traffic Control (ATC) radios Navigation Systems

5. Response to External Field AIRBORNE

6. HIRF Testing

7. HIRF Limits FIXED WING AIRCRAFT

8. Response to External Field ON THE TARMAC

9. Radiation Hazards Personnel (RADHAZ) Fuel (HERF) Ordinance (HERO)

10. Hazard to Personnel 10 W/m 2 maximum averaged over a 6 minute period Corresponds to 61.4 V rms /m

11. Flight Deck Hazard

12. E-Field Map

13. USS Forrestal

15. 162 SAILORS PERISHED

16. Electromagnetic Environmental Effects Safety of flight Radiation Hazards Cosite interference E3E3

17. US AWACS

18. Co-Site Interference Analysis

19. A Gigantic Spreadsheet Problem N Tx = number of transmitters N Rx = number of receivers N b = number transceivers SINGLE-TONE ANALYSIS

20. A Gigantic Spreadsheet Problem N Tx = number of transmitters (8) N Rx = number of receivers (16) N b = number transceivers (12) (548) SINGLE-TONE ANALYSIS

21. Linear Analysis

22. Friis Equation FAR-FIELD C = COUPLING IN dB R = SEPARATION DISTANCE  = WAVELENGTH G = ANTENNA GAIN L = CROSS-POLARIZATION LOSS POL

23. Antennas Antenna gain is directional EXAMPLE ANTENNA PATTERN

24. Field from Isotropic Source

25. Reflections SOURCE SE

26. Diffraction and Reflection SOURCE SE

27. Modified Friis Equation FAR-FIELD C = COUPLING IN dB R = SEPARATION DISTANCE  = WAVELENGTH G = ANTENNA GAIN L = CROSS-POLARIZATION LOSS POL SE = SHIELDING EFFECTIVENESS

28. Nonlinear Effects Harmonic distortion Intermodulation distortion Gain Compression

29. Harmonic Distortion All transmitters generate harmonics. Harmonics can also be generated from a single tone applied to the receiver input circuitry.

30. Intermodulation Distortion (IMD) Two transmitters, one receiver  f = f 1 -f 2 FREQUENCY Weierstrass Approximation Theorem

31. Third-Order IMD Example

32. Two-Tone Combinations N Tx = number of transmitters N Rx = number of receivers N b = number transceivers

33. Two-Tone Combinations N Tx = number of transmitters (8) N Rx = number of receivers (16) N b = number transceivers (12) (5092)

34. Re-Radiated IMD

35. Cross Modulation Modulation from one signal is transferred onto another MOST SEVERE ON AM SIGNALS

36. Cosite Interference Mitigation Options Coupling reduction Filtering Tuning rules Blanking Statistical Characterization Active cancellation

37. Coupling Reduction Separation increase Absorber Cross polarization

38. Filtering

39. Active Cancellation Tx Rx COUPLER AMPLITUDE & PHASE ADJUST +

40. Accuracy Required CONTOURS OF CANCELLATION IN dB

41. Summary E 3 analysis is a significant portion of modern aircraft development. Interference from both internal and external sources must be considered for safety of flight. A thorough cosite interference analysis requires the evaluation of a large number of combinations.