Effects of RF Pulses on Circuits and Systems

Effects of RF Pulses on Circuits and Systems – Pieces MURI Team Experience in EM Penetration and Coupling Pieces CU UH UIC UIUC UM 1

Effects of RF Pulses on Circuits and Systems – Pieces MURI Team Experience Wires and Penetration Accuracy Coupling Enhancement Apertures Building Time Domain FDTD Fast Methods Penetration Methods Integral Freq. Domain Cavity Block House Equations Penetration Methods Backdoor Nonlinear Exterior Experimental Entry Loads Problems Verification CU UH UIC UIUC UM 2

Effects of RF Pulses on Circuits and Systems – Pieces 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 CU UH UIC UIUC UM 3

Effects of RF Pulses on Circuits and Systems – Pieces Wire through Hole in Conductor CU UH UIC UIUC UM 4

Effects of RF Pulses on Circuits and Systems – Pieces Wire through Hole in Conductor CU UH UIC UIUC UM 5

Effects of RF Pulses on Circuits and Systems – Pieces CU UH UIC UIUC UM 6

Effects of RF Pulses on Circuits and Systems – Pieces LIME excitation of vent slots CU UH UIC UIUC UM 7

Effects of RF Pulses on Circuits and Systems – Pieces Wires coupled via a Slot in a Screen CU UH UIC UIUC UM 8

Effects of RF Pulses on Circuits and Systems – Pieces CU UH UIC UIUC UM 9

Effects of RF Pulses on Circuits and Systems – Pieces CU UH UIC UIUC UM 10

Effects of RF Pulses on Circuits and Systems – Pieces 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 CU UH UIC UIUC UM 11

Effects of RF Pulses on Circuits and Systems – Pieces Electric Field Shielding (d. B): Validation of MLFMM code EMCAR 30 cm Measured at Center of cavity 12 cm Ey y k z 30 cm Rectangular Aperture 20 by 3 cm x Note that at resonance relative coupling is increased by 20 d. B as compared to ambient field CU UH UIC UIUC UM 12

Effects of RF Pulses on Circuits and Systems – Pieces Transmission Through Loaded Apertures Transmission vs. Incidence Angle CU UH UIC Transmission vs. Frequency UIUC UM 13

Effects of RF Pulses on Circuits and Systems – Pieces Coupling to a Wire Near a Slotted Cylinder CU UH UIC UIUC UM 14

Effects of RF Pulses on Circuits and Systems – Pieces Plane Wave Exciting Wire in Slotted Tube CU UH UIC UIUC UM 15

Effects of RF Pulses on Circuits and Systems – Pieces Analysis of a Probe Inside a Slotted Cavity CU UH UIC UIUC UM 16

Effects of RF Pulses on Circuits and Systems – Pieces Corroboration of Computed Data CU UH UIC UIUC UM 17

Effects of RF Pulses on Circuits and Systems – Pieces Results Normalized output current for a 1 V source • EIGER (preliminary results) • Measurement (IEEE Trans. EMC, May 1994, pp. 144 -146) -+ 0. 6 m 0. 36 m 0. 4 m CU UH UIC UIUC UM 18

Effects of RF Pulses on Circuits and Systems – Pieces Accurate Methods—Assurance of Accuracy • Penetration into slotted rectangular tube – 2 D • Coupling to probe in nose cone of “mock” missile CU UH UIC UIUC UM 19

Effects of RF Pulses on Circuits and Systems – Pieces Weak Penetration Study CU UH UIC UIUC UM 20

Effects of RF Pulses on Circuits and Systems – Pieces 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. CU UH UIC UIUC UM 21

Effects of RF Pulses on Circuits and Systems – Pieces Penetration into Buildings • Penetration through composite wall – concrete with rebar “shield” • Composite transfer function CU UH UIC UIUC UM 22

Effects of RF Pulses on Circuits and Systems – Pieces 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 (d. B) CU UH UIC Measured Transmission UIUC UM 23

Effects of RF Pulses on Circuits and Systems – Pieces 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. CU UH UIC UIUC UM 24

Effects of RF Pulses on Circuits and Systems – Pieces 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 CU UH UIC UIUC UM 25

Effects of RF Pulses on Circuits and Systems – Pieces Curved Slot in Conducting Surface CU UH UIC UIUC UM 26

Effects of RF Pulses on Circuits and Systems – Pieces CU UH UIC UIUC UM 27

Effects of RF Pulses on Circuits and Systems – Pieces Penetration through Slotted Surface CU UH UIC UIUC UM 28

Effects of RF Pulses on Circuits and Systems – Pieces Fast TDIE analysis: EMC of enclosures Rapid time domain analysis of motherboards/cards, (partial) enclosure, pins, … • • CU UH UIC Approx. 10 K spatial unknowns Broadband analysis = 2 hours UIUC UM 29

Effects of RF Pulses on Circuits and Systems – Pieces Fast TDIE analysis: EMC of enclosures (Cont) Power (d. Bm. W) • Ventilation slot emissions 20 cm 15 cm 17. 5 cm 4. 5 cm 25 cm f (GHz) 25 cm 30 cm Chassis + motherboard + cards CU UH UIC Radiated power for different configurations UIUC UM 30

Effects of RF Pulses on Circuits and Systems – Pieces Fast TDIE analysis: low frequency aspects • Rapid time domain analysis of motherboards with traces, cables, gaps, etc • • CU UH UIC Approx. 3 K 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) UIUC UM 31

Effects of RF Pulses on Circuits and Systems – Pieces Fast TDIE analysis: low frequency aspects (Con’t. ) NA 30 cm 20 cm Comparison of computed |S 21| to the measured result* 2 mm §Excitation fmax = 1 GHz § at fmax = 0. 3 m §ds at fmax = /300 /10 § CU UH UIC UIUC UM 32

Effects of RF Pulses on Circuits and Systems – Pieces 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 500 varistors Voltage (k. V) Magnitude (k. V) 0. 1 m Current (k. A) CU UH UIC UIUC UM 33

Effects of RF Pulses on Circuits and Systems – Pieces Finite Difference Time Domain (FDTD) Modeling • Investigation of EM fields radiated from a localized source inside a buried facility Problem Geometry CU UH 3 -Dimensional FDTD Model UIC UIUC UM 34

Effects of RF Pulses on Circuits and Systems – Pieces Finite Difference Time Domain (FDTD) Modeling (Con’t. ) Tangential E-field at earth surface at t = 65. 8 ns CU UH UIC Radiated E-field in far zone UIUC UM 35

Effects of RF Pulses on Circuits and Systems – Pieces 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” CU UH UIC UIUC UM 36

Effects of RF Pulses on Circuits and Systems – Pieces EMI Threat to Aircraft Systems Airborne Transmitter Picture from NASA-Langley Lightening PEDS Ground-based or ship-board Transmitter External Threat • Coupling from other Aircraft Systems • Natural Environmental Effects (Lightening, Static Electricity) • Man Made Sources External to the aircraft (High Intensity Radiated Fields - HIRF) CU UH UIC Internal Threat • Portable Electronic Devices (PEDS) carried by passengers UIUC UM 37

Effects of RF Pulses on Circuits and Systems – Pieces Antenna Simulation on Full Scale Aircraft CU UH UIC UIUC UM 38

Effects of RF Pulses on Circuits and Systems – Pieces 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 CU UH UIC UIUC UM 39