MURI Team Experience in EM Penetration and Coupling

1. MURI Team Experience in EM Penetration and Coupling Pieces

2. MURI Team Experience

3. Wires, Apertures, Conducting Surfaces • Wire through hole in conducting screen • Wire excited through aperture in conducting screen • Penetration through arrays of slots • Wire-to-wire coupling through slot in screen

4. Wire through Hole in Conductor

5. Wire through Hole in Conductor

7. LIME excitation of vent slots Figure 5.16. Magnetic current induced in vent slot due to dipole-spot excitation

8. Wires coupled via a Slot in a Screen

11. Penetration into and Radiation from Enclosures through Apertures • Penetration into box via slot in sidewall • Penetration through loaded aperture • Coupling to wire in slotted conducting tube • Coupling to wire in box through slot in wall • Wire in box with slots in sidewall -- EIGER

12. 30 cm y 12 cm z x Ey 30 cm k Rectangular Aperture 20 by 3 cm Electric Field Shielding (dB): Validation of MLFMM code EMCAR Measured at Center of cavity Note that at resonance relative coupling is increased by 20dB as compared to ambient field

13. Transmission Through Loaded Apertures Transmission vs. Frequency Transmission vs. Incidence Angle

14. Coupling to a Wire Near a Slotted Cylinder

15. Plane Wave Exciting Wire in Slotted Tube

16. Analysis of a Probe Inside a Slotted Cavity

17. Corroboration of Computed Data

18. 0.6 m - + 0.36 m 0.4 m Results Normalized output current for a 1 V source • EIGER (preliminary results) • Measurement (IEEE Trans. EMC, May 1994, pp. 144 -146)

19. Accurate Methods—Assurance of Accuracy • Penetration into slotted rectangular tube – 2D • Coupling to probe in nose cone of “mock” missile

20. Weak Penetration Study

21. Weak Penetration Study Far-zone electric field due to the probe inside mock missile with partially closed nose cone: hc= 14.6 cm, hb= 118.7 cm, a= 0.0787 cm, b= 7.875 cm, c= 0.2286 cm, d= 4.25 cm, e= 3.1 cm.

22. Penetration into Buildings • Penetration through composite wall – concrete with rebar “shield” • Composite transfer function

23. Modeling of EM Field Penetration into Buildings • Simple models for field penetrations into complex facility walls have been developed, using previously measured data Computed Transmission (dB) Measured Transmission

24. Modeling of EM Field Penetration into Buildings (con’t.) • Example of the transfer functions for a rebar shield alone, one and two layers of concrete (each 0.102 m thick with er = 1, mr = 1, s = 0.1 S/m), and the composite rebar/concrete shield.

25. Time Domain Methods, Fast Methods • Penetration through curved slots • Fast time domain integral equation (TDIE) methods–penetration into enclosures • “Low frequency” considerations of TDIE • Accommodate nonlinear loads • Finite difference time domain (FDTD) methods

26. Curved Slot in Conducting Surface

28. Penetration through Slotted Surface

29. Fast TDIE analysis: EMC of enclosures Rapid time domain analysis of motherboards/cards, (partial) enclosure, pins,… • Approx. 10K spatial unknowns • Broadband analysis = 2 hours

30. 20 cm 10 cm 5 cm 15 cm 1 cm 4.5 cm 17.5 cm 25 cm 25 cm 30 cm 30 cm Fast TDIE analysis: EMC of enclosures (Cont) • Ventilation slot emissions Power (dBmW) f (GHz) Radiated power for different configurations Chassis + motherboard + cards

31. Fast TDIE analysis: low frequency aspects • Rapid time domain analysis of motherboards with traces, cables, gaps, etc • Approx. 3K spatial unknowns • Broadband analysis = 30 mins • Using stable TDIE schemes • Galerkin testing in time (Nedelec / Volakis) • Loop star decompositions • Contrary to FDTD: no timestep limitation (CFL >>> 1)

32. Excitation fmax = 1 GHz •  at fmax = 0.3 m • ds at fmax = /300  /10 Fast TDIE analysis: low frequency aspects (Con’t.) Comparison of computed |S21| to the measured result* NA 30 cm 20 cm 2mm

33. Magnitude (kV) Voltage (kV) Current (kA) varistors Fast TDIE analysis: nonlinear circuitry • We have developed a capability for analyzing lumped nonlinear elements in within TDIE framework. Voltage on the varistor 5 m 0.02 m 0.1 m 500  500 

34. Finite Difference Time Domain (FDTD) Modeling • Investigation of EM fields radiated from a localized source inside a buried facility Problem Geometry3-Dimensional FDTD Model

35. Finite Difference Time Domain (FDTD) Modeling (Con’t.) Tangential E-field at earth surface at t = 65.8 ns Radiated E-field in far zone

36. The Exterior Problem, Fast Frequency Domain Methods • Leakage of field from exterior to interior through cracks, seams, and holes • Leakage of field from exterior to interior through antennas • Fast frequency domain methods (FD) for “massive problems”

37. Airborne Transmitter Lightening PEDS Ground-based or ship-board Transmitter EMI Threat to Aircraft Systems Picture from NASA-Langley External Threat Internal Threat • Coupling from other Aircraft Systems • Natural Environmental Effects • (Lightening, Static Electricity) • Man Made Sources External to the aircraft • (High Intensity Radiated Fields - HIRF) • Portable Electronic Devices (PEDS) carried by passengers

38. Antenna Simulation on Full Scale Aircraft

39. Coupling through Antennas • Antennas are ‘doors’ to coupling from external excitations into the aircraft, tanks, missiles, ships, control centers, etc. • For coupling studies, details such as wires, feed structures and loadings are crucial