6. MIMO Antennas for Mobile Terminal.show

Antenna Engineering
MIMO System
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Wireless standards and MIMO
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SISO and Multipath Fading
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Multiple Antennas improves Signal Quality
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Multiple Antennas improve capacity
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Antenna Polarization
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Cross Polarization
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Correlation coefficient
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Mean Effective Gain
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MEG Ratio
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MIMO antenna design parameters
Low envelope correlation between antennas
Low envelope correlation can result from having sets of antenna patterns
that are diverse in the spatial, phase and polarization senses. In order
words, if all antenna patterns are "looking" in different directions or in di
fferent ways(phase/polarization) one has low correlation.
Large individual antenna mean effective gain (MEG)
MEG refers to the gain of an antenna in particular environment relative
to some reference antenna (e.g. isotropic radiator). In order words, it is a
measure of how well an antenna receives power for a particular scatterin
g environment.
All antennas with roughly the same mean effective gain
The MEG of each antenna needs to be roughly the same for a balanced
system
Low total array reflection coefficient (TARC)
Antennas radiate simultaneously and must have minimal crosstalk pairs
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2x2 MIMO Antenna Design
The typical antenna specification for 2x2 MIMO has the
following goals;
Number of independent antenna ports: 2
Radiation efficiency : As high as possible
Gain balanced ratio (ratio of the gain at each antenna port) :
As high as possible, approaching 1
Correlation coefficient (envelope correlation coefficient between
the two antenna ports) : As low as possible, approaching 0
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Diversity Gain
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Correlation in free space
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Correlation with Scattering object
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Correlation over distance
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Diversity Gain
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Antenna placement (2-antenna array)
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Single Antenna Design (f=2.6GHz)
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Placement Investigation (s-parameters)
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Mutual coupling (2-1)
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Mutual coupling (2-2)
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Mutual coupling (2-3)
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Mutual coupling comparison
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Correlation coefficient comparison
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MIMO Antenna Design
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MIMO Antenna Design
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MIMO Antenna Design
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MIMO Antenna Design
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MIMO Antenna Design
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LTE handset antenna design
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LTE handset antenna design
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LTE handset antenna design
VSWR: <2:1
Efficiency:
30-40%
Patterns
almost
identical
Coupling:
CC: >0.8
-4dB
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LTE handset antenna design
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LTE handset antenna design
VSWR <2.
2:1
Efficiency
50-58%
CC: <0.35
Isolation:
<-13 dB
Significantly different
patterns results in low
envelope correlation
coefficient
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Ex) MIMO Antenna Design
Ground Surface Current and Isolation
Actually position on
ly is not enough
Preferable position
Antenna surface
current distribution
Type A antenna current
-9dB isolation
MIMO Antenna
Type B antenna current
-11dB isolation
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Ex) MIMO Antenna Design
Type 1
Type 2
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Ex) MIMO Antenna Design
Current distribution with slot on the ground
Current induci
ng coupling
Current mag
nitude
Current suppre
ssed
Short end
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Open end
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Ex) MIMO Antenna Design
1/4
slot on PDA ground size
30db suppression
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Ex) MIMO Antenna Design
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Ex) MIMO Antenna Design
1.Without slot
2.With 2.4GHz only
3.With 5.2GHz only
4.With dual slot
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Ex) MIMO Antenna Design
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