Sae Presentation Emc 01

Electromagnetic Compatibility of Conductive Heat Reflecting Automotive

Windows

Charles S. VoeltzelCreative Solutions: Verre

csv

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Electromagnetic Compatibilityy The ability of an electronic system to

function properly in its intended electromagnetic environment.

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IR Reflecting Conductive Windshield

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IR Reflecting vs. IR AbsorbingIR Heat Absorbing

y Green glass – higher iron levelsy Absorbs the sun’s heat becoming hot

to the touch8 Reradiates heat inside of vehicle

IR Heat Reflectingy Conductive metallic coating

8 Sheet Resistance of less than 3ohms/sqr

y Glass reflects the sun’s heat staying cool

y Common in EU, up to 30%y May be mandated by CA – CARB

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Sheet Resistance: Ohms/Sqr

=

1 ohm

1 ohm

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1 ohm

=

5

0

20

40

60

80

100

300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500

Wavelength (nm)

% T

ran

smitt

ance

Ideal Glass

Solex Green Glass

Sekisui HC PVB Southwall Sungate

Sungate EP

Relative Solar Irradiance

% Transmittance by WavelengthNominal 70 % Visible Light Transmission Laminate Configurations

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Solar Performance - Transmittance

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% Reflectance by WavelengthNominal 70 % visible Light Transmission Laminate Configurations

0

20

40

60

80

100

300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500

Wavelength (nm)

% R

efle

ctan

ce

Green Glass Sekisui HC PVB Southwall

Sungate Sungate EP Ideal Glass

Relative Solar Irradiance

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Solar Performance - Reflectance

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AC Fuel Use Reduction

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DeletionAreas covered by black paint.

y Mask or deletey Deletion line should be one continuous line to aid manufacturability. y Keep black band as wide as possible.y Include a third visor black paint area.

Mask/Deletion Line

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Third Visor

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Frequency Selective Surfaces (FSS)

Band Stop Band Pass

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The door of a microwave oven blocks microwave while allowing visible light to pass.

Black = Metal

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Frequency Selective Surfaces

Band Stop Band Pass

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Black = Metal

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Measurement System300MHz – 3GHz horns

HP network analyzer

Computer interface

RF absorbing enclosure

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Uncoated Laminated Glass

-6

-3

0

3

800 1,000 1,200 1,400 1,600 1,800 2,000 2,200 2,400 2,600 2,800 3,000MHz

dB

Uncoated

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Coated Laminated Glass

-30.00

-27.00

-24.00

-21.00

-18.00

-15.00

-12.00

-9.00

-6.00

-3.00

0.00

800 1,000 1,200 1,400 1,600 1,800 2,000 2,200 2,400 2,600 2,800 3,000MHz

dB

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FSS Rectangular Grid Patterns

-9

-6

-3

0

800 1,000 1,200 1,400 1,600 1,800 2,000 2,200 2,400 2,600 2,800 3,000MHz

dB

1mm Grid

3mm Grid

5mm Grid

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FSS Rectangular Grid Patterns

Normalized to:

Air-Gap Glass

800MHz - 3GHz

Uncoated Coated 1mm 3mm 5mm

Average -1.50 -25.90 -1.09 -2.89 -4.62

Min -5.88 -48.02 -2.94 -5.65 -8.08

Max 0.94 -19.31 -0.15 -1.61 -2.68

Range 6.82 28.70 2.79 4.04 5.41

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Periodic Methods of Moments: 0 - 40GHz

-10

-9

-8

-7

-6

-5

-4

-3

-2

-1

0

0 10,000 20,000 30,000 40,000

MHz

dB

0.500.901.001.101.201.401.501.601.701.801.902.005.00 5.0 gls1.30

5mm Laminated Glass

1mm

0.5 mm

5 mm

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LASER Deletion: Radar

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900 microns

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Frequency Selective Surfaces

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< 100 microns

LASER spots overlap to form lines

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Frequency Selective Surfaces

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Provide Laser etched or completely deleted areas for devices mounted on or in close proximity to the windshield.

LASER Treated Areas (3)

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Frequency Selective Surfaces

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Deletion MethodsMasking and Abrasive Wheel

y Periphery8 Black band

y Third Visor8 Toll

LASERy Fine patterningy Frequency Selective Surfaces

8 RF y De-coupling of antennas

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DESIGN GUIDLINESAlternate Locations:

y Consider mounting antennas in other areas.8 Roof or Trunk

8 GPS, Cell, Satilite Radio8 Package shelf

8 RKE, Tire Pressure8 Rear window

8 Screen print Silver

8 Keep dash/IP mount devices (GPS) as close as possible to the bottom front of the windshield

8 maximize the field of view and 8 minimize the size of deletion needed.

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DESIGN GUIDLINESAre specifications based upon function or specific device?

y Specifications are often based upon the capability of a specific antenna rather than what is actually needed for reliable operation.

y An OEM GPS specification calls for either 28dB or 22dB of gain depending upon location: on the roof or in the dash. Which location must meet the 28dB spec.?

y Answer: the roof!

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Conclusions

IR reflecting glazing can improve mileage, lower emissions and increase comfort.

Usage is increasing and may be mandated.

Effective engineered solutions are available to address compatibility issues.y Deployed in millions of vehicles.y Standard on some high end vehicles.

8 Mercedes S-Class in all positions since 20008 Complex electronic systems