Supervised Undergraduate Thesis Audhia Reza

1. Design and Realization of
1.8-2.4 GHz MIMO 2 x 2 Antenna
for Handset Applications
Ir.Audhia Reza
Dr.Ir.Joko Suryana
Laboratory of Radio Telecommunication and Microwave
School of Electrical Engineering and Informatics
Institut Teknologi Bandung INDONESIA
Sunday, November 25, 12

2. Abstract
• A MIMO 2 x 2 antenna for handset application has been proposed.
– The antenna element of the MIMO system is based on a Wideband
Planar Inverted F-Antenna (PIFA) which has been optimized at
1.8-2.4 GHz band.
– The PIFA is compact and small enough for the placement in
handset which has a limited space
– Wideband characteristics of the PIFA is achieved by applying a
meandering shorting strip in place of a normal shorting strip on a
regular PIFA.
• Several MIMO configurations are applied for the dual PIFAs to meet
the required return losses (S11 and S22), mutual couplings (S12 and
S21), and correlation coefficient while maintaining its size to be small
enough for the placement in handset.
• The presence of human head and hand has been simulated and
analyzed to investigate their effects on performance of the antenna.
Sunday, November 25, 12

3. Outline
• The Challenges of MIMO 2x2 Antenna Design
for LTE Handset
• Designing the MIMO 2x2 Antenna Systems
• Performance Comparisons of Simulation and
Measurement Results
• Head and Hand Effects of MIMO 2x2 Antenna
• Conclusions
Sunday, November 25, 12

4. REQUIREMENTS OF MIMO
2X2 ANTENNA FOR LTE
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5. MIMO Systems
• Currently, MIMO systems
are considered as one of
main technology applied
in 4G system to meet the
IMT-Advanced standard.
• MIMO systems provide
better diversity gain for
increasing the SNR and
improving system
performance on
Datarate vs SNR
for various
MIMOs
Sunday, November 25, 12

6. MIMO 2x2 Antenna Design
Challenges
• LTE technology facilitates MIMO to support high
data rate applications. However, integrating several
antennas onto a printed circuit board (PCB) becomes
progressively more difficult as each new generation
of handsets experience miniaturization.
• The closely-spaced antennas produce high mutual
coupling, which opposes the relatively low
correlation between the received signals as required
for effective MIMO performance.
• High port-to-port isolation is required to achieve
the low correlation between closely spaced
antennas.
Sunday, November 25, 12

7. Typical Handset Size
• Current mobile
devices have limited
space.
• A typical smartphone is
about 60 mm wide x
130 mm long.
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8. MIMO 2x2 Antenna Design
• The typical antenna specification for 2x2 MIMO has
the following goals:
1.Number of independent antenna ports: 2
2.Radiation efficiency: as high as possible ~ 100 %
3.Gain balance ratio : as high as possible ~ 1
• ratio of the gain at each antenna port
4.Correlation coefficient : As low as possible ~ 0
• envelope correlation coefficient between the
two antenna ports
Parameter/Impact Space Coupling Correlation Diversity Gain
Space↓ - ↑ ↑ ↓
Coupling ↓ ↑ - ↑ ↓
Correlation↓ ↑ ↑ - ↑
Sunday, November 25, 12

9. MIMO 2X2 ANTENNA DESIGN
Sunday, November 25, 12

10. Element Antenna : Reference
• Reference :
P. W. Chan, H. Wong, and E. K. N. Yung, "Wideband planar inverted-F
antenna with meandering shorting strip," Electronics Letters , vol. 44,
no. 6, pp. 395-396, 2008.
• fc is the fundamental resonant
frequency of PIFA
• C is the speed of light
• L1 and L2 represent length and
width of the planar element of PIFA
• εr represents dielectric permitivitty
of substrate (in this case air, εr = 1)
• W represents the shorting strip
width.
• For 1.8-2.4 GHz, the upper
frequency is set to be 2.2 GHz
• The second resonant frequency
made by the meandering shorting
strip should be < 2.2 GHz
Sunday, November 25, 12

11. Element Antenna : Optimization
Our optimization approach:
• Adjust the ground plane
dimension
• Modify the feeding distance from
the shorting
• Control the height of the planar
element from ground plane
Sunday, November 25, 12

12. Element Antenna : Designed PIFA
• fc is the fundamental
resonant frequency of
PIFA
• C is the speed of light
• L1 and L2 represent
length and width of the
planar element of PIFA
• εr represents dielectric
permitivitty of substrate
(in this case air, εr = 1)
• W represents the shorting
strip width.
• For 1.8-2.4 GHz, the
upper frequency is set to
be 2.2 GHz
• The second resonant
frequency made by the
meandering shorting strip
should be < 2.2 GHz
Sunday, November 25, 12

13. MIMO 2x2 Antenna : Possible
Configurations
• Before applying the MIMO configuration, the designed
element antenna is placed at the top of a PCB that would
act as a handset component board. Then, the MIMO
configuration is applied by placing the second identical
element antenna at the same PCB.
• The placement and positioning of the two antennas is
varied but the placement should not use more than
allowed space of 65 x 100 mm2 PCB. The minimum
spacing required between two antenna in MIMO system
is typically 0,5 λ .
• The best MIMO configuration is when 1st antenna placed
vertically at the top left corner and 2nd antenna placed
horizontally at the bottom right corner  Far VH . In
this configuration, the distance between the two
antennas is 97.72 mm or equal as 0.715 λ.
Sunday, November 25, 12

14. MIMO 2x2 Antenna : Possible
Configurations
VV HH + 45
Far VV Far VH
Sunday, November 25, 12

15. SIMULATION AND
MEASUREMENT RESULTS
Sunday, November 25, 12

16. Simulation and Measurement
Results
• The designed MIMO antenna is then implemented
using FR4 Epoxy.
• The designed and fabricated antenna are shown at
these figure :
Sunday, November 25, 12

17. Simulation and Measurement Results :
Return Loss
• We can see that S11
measurement curve is
deeper and also
wider than simulation
design at 1.72-2.41
GHz.
• The measurement
result for S22 is also
better and operates at
1.74-2.49 GHz.
• It can be concluded
that the specification
required for return
loss is met by the
antenna.
Sunday, November 25, 12

18. Simulation and Measurement Results :
Mutual Coupling
• The figure shows us
that the mutual
coupling between
measurement and
simulation results is
slightly different at
2.3 GHz.
• However, the overall
both gives the result
that S12 dan S21 <
-15 dB for the 1.8-2.4
GHz.
Sunday, November 25, 12

19. Simulation and Measurement Results :
Correlation Coefficients
• The measured
correlation coefficient
is lower than simulated
correlation coefficient.
• However, these results
are still appropriate to
the required coefficient
correlation, i.e. which
must < 0.1 for MIMO
antenna.
• The differences
between measured and
simulated results is
come from the
differences of S
parameters between
simulation and
measurement.
Sunday, November 25, 12

20. Simulation and Measurement Results :
Radiation Patterns # 1st Antenna
Sunday, November 25, 12

21. Simulation and Measurement Results :
Radiation Patterns # 2nd Antenna
Sunday, November 25, 12

22. HEAD AND HAND EFFECTS
Sunday, November 25, 12

23. Simulation and Measurement
Results : Head and Hand Effects
• Effects of the usage of the antenna near human
head and hand to the antenna parameters are
also investigated for analyzing its effect on
performance of the MIMO antenna.
Sunday, November 25, 12

24. Simulation and Measurement
Results : Head and Hand Effects
• The measured return loss for the
MIMO antenna is slightly different
than the simulated data.
• S11 for measurement is < -10 dB
for 1.72-2.34 GHz, meanwhile
simulation gives S11 < -10 dB for
1.74-2.34 GHz.
• S22 for measurement is < -10 dB
for 1.75-2.37 GHz, meanwhile
simulation gives S22 < -10 dB for
1.89-2.35 GHz.
• We missed the 2.4 GHz subband,
but actually we do not use Wifi
Access while putting handset on
that position
Sunday, November 25, 12

25. Simulation and Measurement
Results : Head and Hand Effects
• The measured mutual
coupling for the MIMO
antenna is also slightly
different than the
simulated data.
• Mutual coupling for
measurement and
simulation is < -15 dB
for all frequency,
included the frequencies
outside the 1.8-2.4 GHz
band.
Sunday, November 25, 12

26. CONCLUSIONS
Sunday, November 25, 12

27. Conclusions
• The return loss of PIFA with meandering shorting
strip can be improved by ground plane width
adjustment, planar height adjustment, and feed-
shorting distance adjustment.
• The implemented antenna dimension is compact
and small, i.e 20.5 x 16 mm2 with the shorting
width of 2 mm and planar height 9.5 mm from the
ground plane.
– The MIMO antenna can be fabricated on PCB
which has 65 x 100 mm2 dimension.
• The antenna works well at desired band, i.e 1.8-2.4
GHz for S11 < -10 dB thus can be used for various
modern wireless communications such as
DCS-1800, UMTS, LTE 2,3 GHz, and WLAN-
bluetooth.
Sunday, November 25, 12

28. Conclusions
• The antennas separation by 0.715 λ is enough for
small mutual coupling and correlation coefficient
– The mutual coupling is < -15 dB and correlation
coefficient < 0.1 for the operating band
• Finally, the presence of human head and hand has
been simulated and analyzed to investigate their
effects on performance of the antenna.
– In this case, the return loss is worse at frequency
> 2.35, but this should not be primary concern
as we do not use the WLAN applications on this
position ( putting handset by hand near the
human head )
Sunday, November 25, 12

29. Thank You
Sunday, November 25, 12