2009 SAE presentation of paper "Electromagnetic Compatibility of Conductive Coated IR Reflecting Glazing"

1. Electromagnetic Compatibility of
Conductive Heat Reflecting
Automotive Windows
Charles S. Voeltzel
Creative Solutions: Verre
csv

2. Electromagnetic Compatibility
ability of an electronic system to function
The
properly in its intended electromagnetic
environment.
IR Reflecting
Conductive
Windshield
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3. IR Reflecting vs. IR Absorbing
IR Heat Absorbing
 Green glass – higher iron levels
 Absorbs the sun’s heat becoming hot to the
touch
 Reradiates heat inside of vehicle
IR Heat Reflecting
 Conductive metallic coating
 Sheet Resistance of less than 3ohms/sqr
 Glass reflects the sun’s heat staying cool
in EU, up to 30%
Common
be mandated by CA – CARB
May
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4. Sheet Resistance: Ohms/Sqr
1 ohm
1 ohm
1 ohm
=
=
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5. Solar Performance - Transmittance
% Transmittance by Wavelength
Nominal70% Visible Light Transmission Laminate Configurations
% Transmittance
100
80
60
40
20
0
300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500
Wavelength (nm)
Solex Green Glass
Relative Solar Irradiance
Sekisui HC PVB Southwall Sungate
Ideal Glass
Sungate EP
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6. Solar Performance - Reflectance
% Reflectance by Wavelength
Nominal 70% visible Light Transmission Laminate Configurations
100
% Reflectance
80
60
40
20
0
300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500
Wavelength (nm)
Green Glass Sekisui HC PVB Southwall
Sungate Sungate EP Ideal Glass
Relative Solar Irradiance
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7. AC Fuel Use Reduction
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8. Deletion
Areas covered by black paint.
Mask or delete

Deletion line should be one continuous line to aid manufacturability.

Keep black band as wide as possible.

Include a third visor black paint area. Third Visor

Mask/Deletion Line
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9. Frequency Selective Surfaces (FSS)
The door of a microwave oven
blocks microwave while
allowing visible light to pass.
Band Pass
Band Stop Black = Metal
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10. Frequency Selective Surfaces
Band Stop Band Pass
Black = Metal
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11. Measurement System
300MHz – 3GHz horns
RF absorbing enclosure
Computer interface
HP network analyzer
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12. Uncoated Laminated Glass
3
Uncoated
0
dB
-3
-6
800 1,000 1,200 1,400 1,600 1,800 2,000 2,200 2,400 2,600 2,800 3,000
MHz
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13. Coated Laminated Glass
0.00
-3.00
-6.00
-9.00
-12.00
dB
-15.00
-18.00
-21.00
-24.00
-27.00
-30.00
800 1,000 1,200 1,400 1,600 1,800 2,000 2,200 2,400 2,600 2,800 3,000
MHz
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14. FSS Rectangular Grid Patterns
0
-3
dB
1mm Grid
-6
3mm Grid
5mm Grid
-9
800 1,000 1,200 1,400 1,600 1,800 2,000 2,200 2,400 2,600 2,800 3,000
MHz
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15. FSS Rectangular Grid Patterns
Normalized
Air-Gap Glass
to:
800MHz -
Uncoated Coated 1mm 3mm 5mm
3GHz
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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16. Periodic Methods of Moments: 0 - 40GHz
0
5mm Laminated Glass 0.50
-1
0.90
0.5 mm
1.00
-2
1.10
-3 1.20
1.40
-4 1.50
1.60
dB
-5
1.70
1mm
1.80
-6
5 mm 1.90
2.00
-7
5.00
-8 5.0 gls
1.30
-9
-10
0 10,000 20,000 30,000 40,000
MHz
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17. LASER Deletion: Radar
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18. Frequency Selective Surfaces
900
microns
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19. Frequency Selective Surfaces
< 100 microns
LASER spots overlap to form lines
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20. Frequency Selective Surfaces
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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21. Deletion Methods
Masking and Abrasive Wheel
Periphery
band
Black
Visor
Third
Toll
LASER
patterning
Fine
Frequency Selective Surfaces
RF
of antennas
De-coupling
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22. DESIGN GUIDLINES
Alternate Locations:
 Consider mounting antennas in other areas.
 Roof or Trunk
GPS, Cell, Satilite Radio

 Package shelf
RKE, Tire Pressure

 Rear window
Screen print Silver

dash/IP mount devices (GPS) as close as possible to
Keep
the bottom front of the windshield
maximize the field of view and

 minimize the size of deletion needed.
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23. DESIGN GUIDLINES
Are specifications based upon function or specific device?
Specifications are often based upon the capability of a specific antenna rather than what is

actually needed for reliable operation.
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.?
Answer: the roof!

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24. 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.
in millions of vehicles.
Deployed
on some high end vehicles.
Standard
S-Class in all positions since 2000
Mercedes
 Complex electronic systems
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