Antenna Engineering

MIMO System

2MIMO Antenna

Wireless standards and MIMO

3MIMO Antenna

SISO and Multipath Fading

4MIMO Antenna

Multiple Antennas improves Signal Quality

5MIMO Antenna

Multiple Antennas improve capacity

6MIMO Antenna

Antenna Polarization

7MIMO Antenna

Cross Polarization

8MIMO Antenna

Correlation coefficient

9MIMO Antenna

Mean Effective Gain

10MIMO Antenna

MEG Ratio

11MIMO Antenna

MIMO antenna design parameters

Low envelope correlation between antennasLow 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 different 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 scattering environment.

All antennas with roughly the same mean effective gainThe 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

12MIMO Antenna

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

13MIMO Antenna

Diversity Gain

14MIMO Antenna

Correlation in free space

15MIMO Antenna

Correlation with Scattering object

16MIMO Antenna

Correlation over distance

17MIMO Antenna

Diversity Gain

18MIMO Antenna

Antenna placement (2-antenna array)

19MIMO Antenna

Single Antenna Design (f=2.6GHz)

20MIMO Antenna

Placement Investigation (s-parameters)

21MIMO Antenna

Mutual coupling (2-1)

22MIMO Antenna

Mutual coupling (2-2)

23MIMO Antenna

Mutual coupling (2-3)

24MIMO Antenna

Mutual coupling comparison

25MIMO Antenna

Correlation coefficient comparison

26MIMO Antenna

MIMO Antenna Design

27MIMO Antenna

MIMO Antenna Design

28MIMO Antenna

MIMO Antenna Design

29MIMO Antenna

MIMO Antenna Design

30MIMO Antenna

MIMO Antenna Design

31MIMO Antenna

LTE handset antenna design

32MIMO Antenna

LTE handset antenna design

33MIMO Antenna

LTE handset antenna design

VSWR: <2:1 Efficiency:

30-40%

CC: >0.8Coupling:

-4dB

Patterns almost

identical

34MIMO Antenna

LTE handset antenna design

35MIMO Antenna

LTE handset antenna design

VSWR <2.2:1

Isolation:

<-13 dB

Efficiency 50-58%

CC: <0.35

Significantly different patterns results in low envelope correlation

coefficient36MIMO Antenna

Ex) MIMO Antenna Design

Ground Surface Current and Isolation

37MIMO Antenna

Antenna surface

current distribution

Type A antenna current

-9dB isolation

Type B antenna current

-11dB isolation

Preferable positionActually position only is not enough

Ex) MIMO Antenna Design

MIMO Antenna 38

Type 1

Type 2

Ex) MIMO Antenna Design

Current distribution with slot on the ground

MIMO Antenna 39

Open endShort end

Current magnitude

Current suppressed

Current inducing coupling

Ex) MIMO Antenna Design

1/4 slot on PDA ground size

MIMO Antenna 40

30db suppression

Ex) MIMO Antenna Design

MIMO Antenna 41

Ex) MIMO Antenna Design

MIMO Antenna 42

1.Without slot

2.With 2.4GHz only

3.With 5.2GHz only

4.With dual slot

Ex) MIMO Antenna Design

MIMO Antenna 43