Electromagnetic Compatibility of Conductive Heat Reflecting Automotive Windows Charles S. Voeltzel Creative Solutions: Verre csv
Dec 15, 2014
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