The document summarizes research conducted using simulation software (FEKO) to investigate antenna performance on mobile platforms. It provides three case studies: 1) Using FEKO to simulate different grounding configurations of a GPS antenna mounted on a vehicle's front windshield to determine the optimal design. Measurements matched simulation results which found grounding the antenna improved performance. 2) Simulating placement of three new antennas on a locomotive roof to minimize interference between the antennas while maintaining good performance. Optimal placement was determined. 3) Designing and measuring DSRC antennas for vehicles, including a raised monopole and designs with added directors to increase directivity towards the front/rear of the vehicle. Measurements found designs

1. Applied EMAG Laboratory
The Use of Simulation (FEKO) to Investigate
Antenna Performance on Mobile Platforms
1
Daniel N. Aloi, Ph.D.
Director, Applied EMAG & Wireless Lab
2015 Altair Technology Conference
Ford Motor Company Conference and Event Center
Dearborn, Michigan
May 6, 2015

2. Applied EMAG Laboratory
Overview
• Applied EMAG and Wireless Lab
• FEKO Case Studies
– Antenna Placement
– Antenna Coupling
– Antenna Design
• Conclusions
2

3. Applied EMAG Laboratory
Applied EMAG & Wireless Lab
The Applied Electromagnetics and Wireless
Laboratory at Oakland University was
formed to address the needs created by the
increasing evolution of wireless systems
into our everyday world.
The global proliferation of wireless
technologies onto dynamic platforms has
generated challenging engineering issues in
such areas as antenna design, antenna
placement, signal propagation modeling,
interference, radar and overall wireless
system performance.
The AEWL combines its expertise in
electromagnetics & wireless
communications, along with its
measurement and modeling capabilities to
address these issues.
Mission Statement

4. Applied EMAG Laboratory 4
Measurement & Simulation
Capabilities
Automotive Antenna
Range
• Frequency (10 MHz-6 GHz)
• Satellite Gantry (0°-90° elev.)
• Terrestrial Tower (0° elev.)
• Sirius/XM Certified
• 6-m turntable diameter
• Antenna measurement service
to industry.
Anechoic Chamber
• Frequency (1000 MHz-6 GHz)
• 15’x12’x10’ dimensions
• Line with RF absorbing material
• Component-level antenna
measurements on free space or
ground plane
Modeling
• FEKO SW License
• Wireless InSite SW License
• Matlab/Simulink
Fabrication
• Circuit board plotter
• Metal shop.

5. Applied EMAG Laboratory 5
ANTENNA PLACEMENT EXAMPLE
5
Daniel N. Aloi, Elias GhafariPh.D., Mohammad S. Sharawi and Ashley SteffesM.S., “A
Detailed Experimental Study on the Benefits of Electrically Grounding Interior
Glass Mounted GPS Antennas to the Vehicle Roof,” Microwaves, Antennas &
Propagation, IET 8.10 (2014): 782-793.

6. Applied EMAG Laboratory
Objective
• To study the radiation pattern performance impact of
grounding an interior front-windshield mounted GPS
antenna to the vehicle roofline via simulation as a
function of:
– Ground Strip Width
– Ground Strip Length
6

7. Applied EMAG Laboratory 7
Problem
• Y. Dai, T. Talty and L. Lanctot, GPS Antenna Selection and Place-ment for Optimum
Automotive Performance, IEEE International Symposium on Antennas and Propagation
(APS), pp. 132-135, 2001.
• M. K. Alsliety and D. N. Aloi, ”A Study of Ground Plane Level and Vehicle Level Radiation
Patterns of GPS Antenna in Telematics Applications,” IEEE Antennas and Wireless
Propagation LEtters, Vol. 6, pp. 130-133, 2007.
• M. K. Sliety and D. N. Aloi, ”Correlation Between Antenna Radiation Pattern and Field
Performance for Global Positioning Systems in Telematics as a Function of Antenna
Placement,” IET Microwaves, Antennas and Propagation Journal, Vol. 2, No. 2, pp. 130-
140, 2008.
7
• Front-Windshield Mounted
GPS Antenna Challenges:
– Lack of ground-plane.
– Tilted radiation pattern.

8. Applied EMAG Laboratory 8
GPS Patch on 1m Diameter Ground Plane
GPS Patch on 1m Diameter GP 3D Polar Plot – RHCP Gain

9. Applied EMAG Laboratory
Comparison of ROOF vs. CAR Models
• Simulation Settings:
– f = 1575.42 MHz.
– PEC ground plane to simulate ground.
– AZ=0:2:358
– EL=0:5:90
– A standard off the shelf ceramic GPS
patch antenna with dimensions of 25 ×
25 × 0.4 mm3 was used in this study.
• 12 Simulation Scenarios
– ROOF and CAR models
– Tilt Angle= 75°, 60°, 45°
– Width = 30 mm
– Length = 71mm, 119 mm, 167 mm
– Grounded, Not Grounded
• Patch was tuned for all scenarios to a return
loss of better than 10 dB.
• FEKO COTS package was utilized to conduct
all simulations.

10. Applied EMAG Laboratory
Measurement/Simulation Parameters
105/18/2015

11. Applied EMAG Laboratory 11
Illustration of Surface Currents
Not Grounded Grounded
115/18/2015

12. Applied EMAG Laboratory
3D Polar Plots / RHCP Gain / L = 71 mm

13. Applied EMAG Laboratory
ECDF Plot / RHCP Gain / L = 71 mm

14. Applied EMAG Laboratory
3D Polar Plots / RHCP Gain / L = 119 mm

15. Applied EMAG Laboratory
ECDF Plot / RHCP Gain / L = 119 mm

16. Applied EMAG Laboratory
3D Polar Plots / RHCP Gain / L = 167 mm

17. Applied EMAG Laboratory
ECDF Plot / RHCP Gain / L = 167 mm

18. Applied EMAG Laboratory
SIM-ROOF
Percentage of RHCP Gain Values ≤ -5.0 dBic
28.9
14.8
21.4
23.1
14.4
21.8 22.8
16.4
24.8
29.8
25.8
22.5
26.9 26.1
20.9
34.9
24.4
38.4
0
5
10
15
20
25
30
35
40
45
T1-L1 T1-L2 T1-L3 T2-L1 T2-L2 T2-L3 T3-L1 T3-L2 T3-L3
Grounded
Not Grounded

19. Applied EMAG Laboratory
SIM-CAR
Percentage of RHCP Gain Values ≤ -5.0 dBic
20 20.2
21.9
24.5
31.9
20.2
26.4
28.7
30.2
35.2
33.6
38.5
46.2
40
43
44.8
50.8 50.5
0
10
20
30
40
50
60
T1-L1 T1-L2 T1-L3 T2-L1 T2-L2 T2-L3 T3-L1 T3-L2 T3-L3
Grounded
Not Grounded

20. Applied EMAG Laboratory
Measurements
20

21. Applied EMAG Laboratory
MEAS-ROOF
Percentage of RHCP Gain Values ≤ -5.0 dBic
8.5
20.8
17.2
7.3
19.7
17.6
10.6
17.4
25.4
7.6
18.2
22.7
7.4
25.4
27.5
6.8
23
48.9
0
10
20
30
40
50
60
T1-L1 T1-L2 T1-L3 T2-L1 T2-L2 T2-L3 T3-L1 T3-L2 T3-L3
Grounded
Not Grounded

22. Applied EMAG Laboratory
Conclusions
• Show why ROOF model is representative of a CAR model.
– Simulations conducted on grounding strip at constant tilt angle and
ground strip width while varying the ground strip length.
– Repeated for CAR and ROOF models.
– Compared Grounded vs. Non-Grounded Results
– Trends were the same for both models (albeit roof more pronounced),
hence a ROOF model was used in measurements.
• Measurements were conducted at an automotive antenna
measurement facility.
– Results were similar to simulation results.
– Grounding antenna to vehicle roof does clearly improve GPS antenna
radiation pattern.
– Grounding strip is significant cost in high-volume production
environments adding cost.
– Cost vs. performance?

23. Applied EMAG Laboratory 23
ANTENNA COUPLING EXAMPLE
23

24. Applied EMAG Laboratory
Objective
To use a full-wave, three-dimensional electromagnetic
simulation tool to determine the ideal placement of
three antennas that are in the same frequency band on
a locomotive rooftop configuration without modifying
or removing its existing antennae. Figures of merit for
this analysis include VSWR, Gain Pattern and Isolation.
24

25. Applied EMAG Laboratory 25
Roof Configuration – Isometric View
5/18/2015
Applied EMAG, Inc. 25
Placemen
t
Volume

26. Applied EMAG Laboratory
New Antennas To Be Installed
• Antenna #1
– Frequency: 380-430 MHz
– Dim.: (HxWxL): 24.2 cm x 10.2 cm x 9.8 cm
– Maximum Gain: 2.0 dBi
• Antenna #2
– Frequency: 450-470 MHz
– Dim.: 8.1 cm OD x 10.7 cm
– Maximum Gain: UHF: 2.0 dBi
• Antenna #3
– Frequency: 410-430 MHz
– Dim. (HxWxL): 16 cm x 12 cm x 11 cm
– Maximum Gain: 2.0 dBi
26

27. Applied EMAG Laboratory
Optimal Antenna Placement Criteria
• Goal is to not modify existing roof antenna configuration.
• Establish a volume to place new antennas:
– Height of volume is top of AC unit.
– Placement area extends between AC unit and rear roof profile.
• New antenna locations should be insulated from the roof.
• Account for shading of objects on the roof such as the rear
roof and AC unit.
• Minimize isolation and de-sensitization between new and
existing antennas.
• VSWR of new antennas should not be degraded due to
objects near it on the roof.
27

28. Applied EMAG Laboratory
Antenna Simulation Strategy
• Design component-level antennas on a finite
GP.
• Add component-level antennas to roof
configuration.
• Monitor following performance metrics:
– VSWR
– Isolation/Desensitization between antennas.
28

29. Applied EMAG Laboratory
Antenna #1 (380-430 MHz)
29
• Inverted-F Antenna - VLP
• PEC Materials
• Antenna Dimensions
– Length: 24.2 cm
– Width: 10.2 cm
– Height: 9.8 cm
• Ground Plane Dimensions
– 76.2 cm x 76.2 cm

30. Applied EMAG Laboratory
Antenna #2 (450-470 MHz)
• Scaled version of Antenna #1.
30

31. Applied EMAG Laboratory
Antenna #3 (410-430 MHz) – Existing Antenna
31
• λ/4 Monopole - VLP
• PEC Materials
• Antenna Dimensions
– Length: 16.8cm
– Diameter: 1 cm
• Ground Plane Dimensions
– 76.2 cm x 76.2 cm

32. Applied EMAG Laboratory
Roof Layout – Isometric View
5/18/2015 32
ANT#3
410-430
ANT#1
380-430
ANT#2
450-470

33. Applied EMAG Laboratory
Figures of Merit – Isolation Testing
• Desensitization:
– Forward transmission gain between TX and RX
antennas @ TX resonant frequencies.
• Spurious Emissions
– Forward transmission gain between TX and RX
antennas @ RX antenna resonant frequencies.
PRX fTX( ) = PTX fTX( )+ S12 ( fTX )
PRX fRX( ) = PTX fRX( )+ S12 ( fRX )

34. Applied EMAG Laboratory
Simulated Roof – Return Loss
34
ANT#1
ANT#2
ANT#3

35. Applied EMAG Laboratory
Simulated Roof – Port-to-Port Isolation
5/18/2015 35
ANT#1-ANT#3
ANT#1-ANT#2
ANT#2-ANT#3

36. Applied EMAG Laboratory 36
Roof Configuration Measured
36

37. Applied EMAG Laboratory
Isolation Summary
ANT#1 (380-430)
To
ANT#3 (410-430)
ANT#1 (380-430)
To
ANT#2 (450-470)
ANT#3 (410-430)
To
ANT#2 (450-470)
410-420
MHz
450-470
MHz
410-420
MHz
450-470
MHz
410-420
MHz
450-470
MHz
Simulated -34 N/A -30 -20 -30 -32
Measured -33 N/A -26 -24 -40 -36
37
• Bandpass filter centered around HOT frequencies should be used.
• Difficult to achieve 47 dB of isolation or better between the two TETRA antennas in
the 410-420 MHz band.
• Measurements were lower than what is simulated.
- Worst case scenario is the C21 roof.
- Will measure isolation in C21 roof this week.

38. Applied EMAG Laboratory 38
ANTENNA DESIGN EXAMPLE
38
Elias Ghafari, Andreas Fuches, Huzefa Bharmal and Daniel N. Aloi, “On-Vehicle
DSRC Antenna Elements Comparison Study,” ICEAA – IEEE APWC 2014, Palm
Beach, Aruba, August 3-9, 2014.

39. Applied EMAG Laboratory
Research Objective
• NSF Research Experience for Undergraduate
Students were given a 10 week project to
design a directive antenna for DSRC
applications.
• Required to simulate, fabricate and measure
the antenna.
• Results are presented here.

40. Applied EMAG Laboratory 40
DSRC Overview
• The Dedicated Short Range Communications (DSRC) system is a new standard intended for
inter-vehicular communications to improve traffic safety for Intelligent Transportation Systems
(ITS).
• The system is intended for inter-vehicular communications (V2V) and for vehicles-to-
infrastructure (V2I) communications [1].
• The DSRC system’s applications include vehicular safety such as intersection collision
avoidance, emergency vehicles warning, rollover warning and highway-rail intersection
warning, as well as public services such as electronic toll collection and parking payment.
• The DSRC standards established in Europe specify the operational frequency bands and
system’s bandwidths.
• In the USA, the frequency band 5850MHz – 5925MHz has been allocated for the DSRC system
to be used by the ITS

41. Applied EMAG Laboratory
DSRC Antenna Design Challenges
• Multi-band automotive antennas such as
Cellular/LTE/GPS/SDARS are in a single radome in the
center of the rear roof-line.
• Typical roof profiles have a 10 degree slope for the
rear of the roof to the apex of the roof.
• A quarter-wave monopole at 5.9 GHz has a height of
approximately 1.25 cm which is below the apex of
the roof-line.
• 3-5 dB of gain is lost toward the front of the vehicle.

42. Applied EMAG Laboratory
Antenna Design Objective
• The goal of this research
was to take an omni-
directional antenna and
make it more directive
toward the front/rear of the
vehicle.
• Result is extended range of
the DSRC signal for safety of
life applications.

43. Applied EMAG Laboratory
Antenna Designs
• A raised monopole was
tuned to resonate between
5862.5 MHz and 5937.5 MHz
• Simulations in FEKO were
conducted initially to come
up with dimensions for
optimized raised monopole
by itself and with 1, 2 and 3
directors.
• Antennas were then
fabricated on Rogers
RO3003 laminate.
9.7 10.9 12.1
1.9 10.8 13.4 12.0
14.7
11.89.5
7.8
1.9
• All units in mm.
• Width of all directors
and air gaps are 0.5
mm
• Printed of Rogers
RO3003 laminate
• 0.13mm thickness
• εr = 3.0

44. Applied EMAG Laboratory
DSRC Antenna Measurements
• All antenna samples were
measured on a 1-meter
diameter rolled edge ground
plane.
• All antennas tuned to VSWR
better than 2.5:1.
• Antenna was mounted
perpendicular to ground
plane.
• Performance metrics were
maximum gain and linear
average gain at antenna
horizon.
Start Stop Increment
Frequencies 5862.5 MHz 5937.5 MHz 13.5 MHz
Theta Points 0 degrees 90 degrees 5 degrees
Phi Points 0 degrees 360 degrees 2 degrees

45. Applied EMAG Laboratory
Raised Monopole

46. Applied EMAG Laboratory
Raised Monopole with 1 Director

47. Applied EMAG Laboratory
Raised Monopole with 2 Directors

48. Applied EMAG Laboratory
Raised Monopole with 2 Directors

49. Applied EMAG Laboratory
Comparison of All Antenna Types
Avg.
Gain
(dBi)
Max.
Gain
(dBi)
Min. Gain
(dBi)
Monopole 0.8 2.9* -2.0
Monopole Plus 1 Director
Per Side 1.5 3.7 -1.3
Monopole Plus 2 Directors
Per Side 1.6 4.3 -1.7
Monopole Plus 3 Directors
Per Side 2.2 5.2 -1.5
* occurred at direction at phi angle that represented side of a
vehicle.

50. Applied EMAG Laboratory
Conclusions
• Results for a DSRC antenna were presented for an
NSF REU program at Oakland University.
• Directors were added to an omni-directional and
increased the maximum gain from 2.9 dBi to 5.2 dBi
for a raised monopole and a raised monopole with 3
directors, respectively.
• Resulting antenna yields increase DSRC signal range
toward the front/rear of vehicle for safety of life
applications.

51. Applied EMAG Laboratory
Questions
51