effects of rf pulses on circuits and systems – pieces umcuui c 1 uiucuh muri team experience in em...

Effects of RF Pulses on Circuits and Systems – Pieces

UMCU UIC

1UIUCUH

MURI Team Experience in EM Penetration and Coupling

Pieces


UMCU UIC

2UIUCUH

MURI Team Experience

Wires and

Apertures

Penetration Accuracy Enhancement

Coupling

Building

Penetration

Time Domain Methods

FDTD Fast

Methods

Integral Equations

Freq. Domain

Methods

Cavity Penetration

Block House Penetration

Backdoor Entry

Nonlinear Loads

Exterior Problems

Experimental Verification


UMCU UIC

3UIUCUH

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


UMCU UIC

4UIUCUH

Wire through Hole in Conductor


UMCU UIC

5UIUCUH

Wire through Hole in Conductor


UMCU UIC

6UIUCUH


UMCU UIC

7UIUCUH

co n s tan t

x

y

LIME excitation of vent slots


UMCU UIC

8UIUCUH

Wires coupled via a Slot in a Screen

Matched Coax

Z0

V0

BackSide Probe

Finite LengthNarrow Slot

RadiatingAntenna

Driven Coax

Metal Screens


UMCU UIC

9UIUCUH

x

z

2L =

2H a = / 2

2H w = / 2

d a = / 2

d w = / 2

a = 135 o


UMCU UIC

10UIUCUH

x

z

2L =

2H a = / 2

2H w = / 2

w = - 45 o

d a= / 2

d w = / 2

a = 135 o


UMCU UIC

11UIUCUH

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


UMCU UIC

12UIUCUH

Electric Field Shielding (dB): Validation of MLFMM code EMCAR

0 0.2 0.4 0.6 0.8 1-20

-10

0

10

20

30

40

50

Frequency in terms of GHz

Ele

ctr

ic F

ield

Sh

ield

ing

(d

B)

Electric Field Shielding vs. Frequency

MLFMMMeasured data

y

x

zEy

k

30 cm

30 cm

12 cm

Rectangular Aperture 20 by 3 cm

Measured at Center of cavity

Note that at resonance relative coupling is increased by 20dB as compared to ambient field


UMCU UIC

13UIUCUH

Transmission Through Loaded Apertures

Transmission vs. Incidence Angle Transmission vs. Frequency

feed

e

r1

e

r2

e

r3

e

r4


UMCU UIC

14UIUCUH

Coupling to a Wire Near a Slotted Cylinder

Infinite PECTube

Thin-WireAntenna

Narrow Slot

Infinite PECTube

Thin-WireAntenna

Narrow Slot


UMCU UIC

15UIUCUH

Plane Wave Exciting Wire in Slotted Tube

b w h

aai

/ . , / . , / .

/ , / . ,

0 2 0 01 2 0 5

0 0 00091 0


UMCU UIC

16UIUCUH

Analysis of a Probe Inside a Slotted Cavity

x

y

a - a

- b

b

L - L

Z g

V g

()

()

PEC

Cavity

z

y

b

-b

Aperture

Original Problem( Valid everywhere )

Probe

Z g

V g

d

h

c

PEC Cavity


UMCU UIC

17UIUCUH

Corroboration of Computed Data


UMCU UIC

18UIUCUH

Results

• EIGER (preliminary results)

• Measurement (IEEE Trans. EMC, May 1994, pp. 144 -146)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0.4 0.45 0.5 0.55 0.6 0.65 0.7

Frequency (GHz)

No

rma

lize

d O

utp

ut

Cu

rre

nt

Normalized output current for a 1 V source

+ -

0.4 m

0.6 m

0.36 m


UMCU UIC

19UIUCUH

Accurate Methods—Assurance of Accuracy

• Penetration into slotted rectangular tube – 2D

• Coupling to probe in nose cone of “mock” missile


UMCU UIC

20UIUCUH

Weak Penetration Study


UMCU UIC

21UIUCUH

Weak Penetration Study

Y G

I G

2d

2e

2c

2a

ahch

bh

2b

0 20 40 60 80 100 120 140 160 180 (degrees)

0

1E-006

2E-006

3E-006

4E-006

5E-006

6E-006

|E |

no

rm

closed-bodyscatterer method

short-cct curent methodaperture method

/ 0.1, ah e dl = ¹

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.


UMCU UIC

22UIUCUH

Penetration into Buildings

• Penetration through composite wall – concrete with rebar “shield”

• Composite transfer function


UMCU UIC

23UIUCUH

Modeling of EM Field Penetration into Buildings

Concrete Layers (d, w , w , w )

Rebar Shield (wire radius r w

mesh spacing a w )

Equivalent shield

Computed Transmission (dB) Measured Transmission

• Simple models for field penetrations into complex facility walls have been developed, using previously measured

data


UMCU UIC

24UIUCUH

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 r = 1, r =

1, = 0.1 S/m), and the composite rebar/concrete shield.


UMCU UIC

25UIUCUH

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


UMCU UIC

26UIUCUH

Curved Slot in Conducting Surface


UMCU UIC

27UIUCUH


UMCU UIC

28UIUCUH

Penetration through Slotted Surface


UMCU UIC

29UIUCUH

Rapid time domain analysis of motherboards/cards, (partial) enclosure, pins,…

• Approx. 10K spatial unknowns

• Broadband analysis = 2 hours

Fast TDIE analysis: EMC of enclosures


UMCU UIC

30UIUCUH

Fast TDIE analysis: EMC of enclosures (Cont)

Radiated power for different configurations

Pow

er

Pow

er

(dB

mW

)(d

Bm

W)

f (GHz)f (GHz)

• Ventilation slot emissions

17.5 cm 4.5 cm

25 cm25 cm

5 cm10 cm

1 cm

20 cm

30 cm

30 cm

15 cm

Chassis + motherboard +cards


UMCU UIC

31UIUCUH

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)


UMCU UIC

32UIUCUH

NA

Fast TDIE analysis: low frequency aspects (Con’t.)

2mm

30 cm

20 cm

60 cm

60 cm

Excitation fmax = 1 GHzExcitation fmax = 1 GHz

at fmax = 0.3 mat fmax = 0.3 mds at fmax = ds at fmax = /300 /300 /10/10 2707

SN

Comparison of computed |S21| Comparison of computed |S21| to the measured resultto the measured result**

-90

-80

-70

-60

-50

-40

-30

-20

-10

0.1 1

ALF-PWTDmeasurement

|S21

| (dB

)

frequency (GHz)


UMCU UIC

33UIUCUH

Fast TDIE analysis: nonlinear circuitry

We have developed a capability for analyzing lumped nonlinear elements in within TDIE framework.

1/0 0( ) ( )v i v i i

0 01000 V, 0.1 A

=30

v i

varistorsvaristors

-1 0 1-2

-1

0

1

2

Current (kA)

Vol

tage

(kV

)

0 0.5 10

10

20

30

40

50

Ma g

nitu

d e (

kV)

( )t s

0 0.02 0.04 0.06 0.08 0.1-0.4

-0.2

0

0.2

0.4

0.6

0.8

1 PWTD-line1PWTD-line2ref-line1 ref-line2

( )t s

Voltage on the varistorVoltage on the varistor

5 m5 m

0.1 m0.1 m 500 500 500 500

0.02 m0.02 m

k̂

excE


UMCU UIC

34UIUCUH

Finite Difference Time Domain (FDTD) Modeling

• Investigation of EM fields radiated from a localized sourceinside a buried facility

Earth surface

z

x

Ex componentplotted along this line

Vertical antennaL = 1.74 ma = 0.1 cm

Excitation voltagesource Vo(t)

+

0.7 m

Problem Geometry 3-Dimensional FDTD Model

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43

Cell no.

43

41

39

37

35

33

31

29

27

25

23

21

19

17

15

13

11

9

7

5

3

1

Region #1 - Free space

Region #2 - Earth

Region #3Concrete

Air-earth interface

Perfect conductor

(free space)

Cell no.


UMCU UIC

35UIUCUH

Finite Difference Time Domain (FDTD) Modeling (Con’t.)

Tangential E-field at earth surface at t = 65.8 ns

0 2E-7 4E-7 6E-7 8E-7Tim e (s)

-8 .0E -5

-6.0E-5

-4.0E-5

-2.0E-5

0.0E+0

2.0E-5

4.0E-5

6.0E-5

8.0E-5

rE (t)

C ase 6 = 45 deg. = 0 deg.

rEcom ponent

rEcom ponent

Radiated E-field in far zone


UMCU UIC

36UIUCUH

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”


UMCU UIC

37UIUCUH

EMI Threat to Aircraft SystemsAirborne Transmitter

Ground-based orship-board Transmitter

PEDSLightening

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)

Internal Threat

• Portable Electronic Devices (PEDS) carried by passengers

Picture from NASA-Langley


UMCU UIC

38UIUCUH

Antenna Simulation on Full Scale Aircraft


UMCU UIC

39UIUCUH

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

Patch or array

Vout

feed

e

r1

e

r2

e

r3

e

r4

effects of rf pulses on circuits and systems – pieces umcuui c 1 uiucuh muri team experience in em...

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