This document discusses car antennas and the potential for transparent antennas. It begins by outlining common car antenna types and frequency spectrums used. Requirements for car antennas include aesthetics, manufacturability, durability and more. Transparent conductors that could enable transparent antennas, like indium tin oxide, are then examined. Finally, the document explores using grid antenna designs made of transparent conductors as an alternative to traditional antennas, though transparency would lower their radio frequency performance.

1. Car Antennas
Luis Brás, Nuno Carvalho,
Pedro Pinho
Instituto de Telecomunicações - Aveiro, Portugal
bras@ua.pt
© 2005, it - instituto de telecomunicações. Todos os direitos reservados.

2. Outline
•
•
•
•
•
Introduction
Car antennas
Transparent Conductors
Transparent Antennas
Conclusions
2

3. Services of today
•
•
•
•
•
•
•
GSM/UMTS
Elect. Toll Collec. (ETC)
Satelitte Radio
DVB-S
Tire Pressure... (TPMS)
Remote Key Entry (RKE)
...
3

4. Frequency Spectrum
L1/L2-GPS
1227/1575 MHz
GSM
824 - 960 MHz
TV
470 – 880 MHz
RKE/TPMS
315 – 433 MHz
FM-Radio
78 – 108 MHz
GSM
1710 - 1990 MHz
WiFi/Bluetooth
2400 - 2500 MHz
ETC
5800 MHz
V2V V2I
5900 MHz
Satellite TV
12200 - 12700 MHz
Radar Collision
Detection System
22000 – 26000 MHz
76000 – 77000 MHz
AM-Radio
0.5 – 1.7 MHz
Frequency (MHz)
4

5. Car Antenna requirements
• System requirements (RP, BW, polarization)
• Vehicular requirements
•
•
•
•
•
•
Aesthetics
Manufacturability
Weather resistance
Weight/Cost
Vandalism
Damage resistance
(car wash, tree branches,...)
5

6. Outline
•
•
•
•
•
Introduction
Car antennas
Transparent Conductors
Transparent Antennas
Conclusions
6

7. Car Antennas (1)
7
AM/FM (helical antenna)
1
3
2
5
4
6
8
7
GPS/cellular design
(Patch/IFA/Slot Antenna)

8. Car Antennas (2)
7
Satellite TV Antenna
1
3
2
5
4
6
8
8
(Phased Array)

9. Car Antennas (3)
7
AM/FM
1
3
2
5
4
6
8
DAB
Traffic Msg. Control (TMC)
(Mendered Microstrip)
9

10. Car Antennas (4)
7
ETC (BendMonopole/IFA)
1
3
2
5
4
6
8
10
Cellular (Dual Band Microstrip)
GPS (CP Patch)

11. Car Antennas (5)
7
AM/FM
1
3
2
5
4
6
8
DAB
TV
GPS
(Mendered Microstrip)
11

12. Car Antennas (6)
7
Automotive Radar Antenna
1
3
2
5
4
6
8
12
(Microstrip Antenna Array)

13. Car Antennas (7)
7
1
3
2
5
4
6
8
13
Tire Pressure Monitoring
Systems (TPMS)
(Microstrip mendered)

14. Car Antennas (8)
7
Remote Start engine (RSE)
1
3
2
5
4
6
8
14
Remote Keyless entry (RKE)
(loop, bend & mendered
Monopole)

15. Implemented Antenna for DSRC
Omnidirectional Microstrip Array
0o
0 dB
-30o
30o
Measured
Simulated
-10
-60o
60o
-20
-30
-90o
90o
-30
-20
-120o
120o
-10
-150
o
0 dB
180
15
o
150o

16. We defined new requirements
•
Higher Gain
•
•
Beam Control
Reduced Impact
to the driver view
Directive transparent Antennas
Beamforming network
System integration
16
Array
Beamforming Networks
Transparent Antenna

17. Outline
•
•
•
•
•
Introduction
Car antennas
Transparent Conductors
Transparent Antennas
Conclusions
17

18. Transparent Conductors
Transparent
Conductor
Characteristic
Indium Tin
Oxide (ITO)
Most commonly used, durable, chemical resistance
to moisture, can be precisely etched
Indium Zinc Oxide
(IZO)
Is used quite often in the LCD’s, easily etchable,
but not as durable as ITO
Zinc Oxide with
Aluminum (AZO)
Lower cost and relatively good optical transmission,
lower chemical resistance to moisture
Fluorine doped Tin
Oxide (FTO)
Difficult to etch fine patterns has made its use
primarily for plasma displays
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19. Transparent Conductors (common application)
Advantages
Low production cost
High resistance to dust and water
Best used with a finger, gloved or stylus
Best suited for handwriting recognition
Advantages
Looks brighter and sharper
Highly touch sensitivity
Supports multi-touch
Disadvantages
Disadvantages
Not too sensitive
Poor contrast
Does not support multi-touch
Not working with simple gloves
More expensive
Glass is more prone to breaking
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20. Outline
•
•
•
•
•
Introduction
Car antennas
Transparent Conductors
Transparent Antennas
Conclusions
20

21. Transparent Antennas
Conductive films can be used for antennas, however with poor
radio frequency performance...
ALTERNATIVE?
Grid antennas...
21

22. Grid Antennas (1)
Reference Antenna
Space between metal strips
(100 um, 200 um, 300 um)
22

23. Grid Antennas (2)
Reference Antenna
Space between metal strips
(100 um, 200 um, 300 um)
23

24. Conclusions
• Transparent antennas can be a solution for car antennas
• ITO based antennas can be a solution, however with
poor RF performance
• Grid antennas are a valid alternative
• Transparency is inversely proportional to antenna
efficiency
24

25. Thanks for your attention…
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