02 Simulation of 5G Antenna Design CST

7/24/2019 02 Simulation of 5G Antenna Design CST

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CST COMPUTER SIMULATION TECHNOLOGY | www.cst.com


Simulation of 5G /

MIMO Antennas Design

Zeev Iluz

Advanced Wireless Technologiesby ROHDE&SCHWARZ


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1. 5G Motivation and Challenges

2. Antenna Array Simulation, MIMO post-processing

3. Mobile Device Antenna Array Example

4. Huawei MIMO Base Station Demonstrator

Agenda


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Consumer device bandwidth requirements increasing at

rapid rates

Historical (4, 3G) bands below 3 GHz increasingly

crowded

Push for 28+ GHz frequency for 5G

subject to relatively high atmospheric attenuation

- smaller wavelength more susceptible to multipath loss

5G Motivation and Challenges


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5G Motivation and ChallengesEfficiency is critical, Gain of 12 dBi for mobile device and 25 dBi targeted

Gain cannot come at the expense of coverage beam steered arrays ideal solution

Diversity Gain can also be leveraged - MIMO

High frequency and array topology pose simulation challenges (memory, system

complexity)


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Small ArraysLarge Arrays

Antenna Arrays Categories


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All elements need to be simulated.

Small Arrays


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Use Combine Results and Correlation Coefficient result

templates to achieve a desired beam shape.

Purely postprocessing, no further 3D simulations

needed!

Array Postprocessing

All amplitudes = 1

How can I achievea pattern like this?

Amplitudes = ????


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Template Based

Postprocessing as aSimulation type

Parameters foramplitude weights

Desired beam shape Achieved beam shape

Array PostprocessingInitial beam shape


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Can be approximated as an

infinite array whichrequires the simulation of

only a single element.

To include edge effects

and other physical

realities, the entire array

needs to be modeled.

Large Arrays


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CST ARRAY WIZARD


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CST Array Wizard Sim Proj

Spacing X, Y = 100Angle 60


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Drag&Drop your Unit Array Element


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Set Elements Active/Passive/Empty


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Finite Array Sim. Proj.


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MIMO Antennas


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Communication NetworksCommunication antennas need to cope with a complex environment

Tilted reflecting planes change

signal polarization Cross Polarization Rate (XPR)

All base-station antennas are

placed near the horizontal plane

Mean Effective Gain (MEG)

Multi-path signal transmission

may lead to destructive signal

overlay, resulting in local deep

dips (called Rayleigh-Fading)

Diversity/MIMO

MIMO Antenna Systems for Advanced CommunicationWebinarhttps://www.cst.com/Applications/Article/MIMO-Antenna-Advanced-Communication


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Diversity / MIMO Antennas

Multiple antennas (antenna diversity)

may overcome this problem

Simple Maximal Signal Diversity GainSimple Maximal Signal Diversity Gain

Multi-path signal transmission may

lead to destructive signal overlayresulting in local deep dips

(called Rayleigh-Fading)

Antenna 1

Antenna 2

best of (diversity gain)


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Diversity / MIMO Antennas

Load farfield of second antenna

Select from:

Diversity Gain Envelope Correlation Coefficient

Multiplexing Efficiency

Mean Effective Gain

Envelope Correlation from Farfield: Envelope Corr. from S-Parameters:


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Mobile Antenna Array

Element -> Array Design

Device level performance

System level performance


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Antenna Magus


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Mobile Antenna Element Design

Magus Antenna Synthesis generates initial square

patch design for 28 GHz operating frequency


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Mobile Antenna Element Performance

Magus also provides

performance estimation for

initial design qualification

Initial design is clearly

approximate Microwave

Studio can be used to optimize

and modify


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Results

Retuned for 28 GHz, at the expense ofimpedance match quality


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Finite Array Generation


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Finite Array Performance


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Theta = 15 deg

Phi = 30 deg

Theta = 0 deg

Phi = 0 deg

Best Achievable PatternEnvelope


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Theta=10

Theta=45 Theta=85

Achievable ArrayPatterns


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Installed Performance


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System Assembly Modelling

System Assembly Modelling providesconvenient layout assembly to bring inphone + other antenna models

Several copies of array independentlyplaced and parameterizable


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Layout Modelling

After wiring system, switch to layout view

and align antenna arrays


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Lower hemispherical array needs

to be flipped to aim downward

Rotate on axis for diversity

Layout Modelling


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Simulation Task

In this case, all models will

be solved together in 3D byMWS T solver


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Simulation Performance

3.5 Minutes simulation time per excitation on dual CPU workstation with nVIDIA

Kepler 20 GPU (10% GPU capacity)

3.48 GB of system Memory utilized for initial Matrix Calculation


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Installed Performance - Coupling

Both arrays operating (boresight), pattern intact

In band coupling to WIFI antenna, GPS coupling at 5Goperating freq


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Installed Performance - Coupling


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Installed Performance - Envelope

Relatively, low coupling to GPS at 28 GHz, but radiation angles towards GPS antenna

are affected

Best Achievable Pattern envelope clearly shows performance degraded


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Cosite Interference / RF Interference

Performance degradation when multiple RF systemsare co-located in a common environment.


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Mobile Phone Receiver Sensitivity

GPS AntennaWiFi Antenna

Tri-Band CellularAntenna

Clock


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Coupling Matrix

Cellular-WiFi Coupling

Cellular-GPS Coupling

WiFi-GPS Coupling


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Transmitter / Receiver Definition

Transmitter

Defined by:

Excitation spectrum (signal) Filter Amplifier

Library

Receiver

Defined by:

Sensitivity spectrum Filter Amplifier

Library


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CST DS Interference Task


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Violation Matrix


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Effects of Hand Model

Top hemisphere array is largely unaffected

Bottom array highly dependent on finger proximity


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MIMO Base Station Array Example

[1] Konstantinos Prionidis, MIMO Configurable Array for Sector / Omni-Directional Coverage, Department of Signals& Systems, Chalmers University of Technology, Gothenburg, Sweden 2014


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-Novel antenna array concept study for small cell sizes(higher capacity and efficiency), 25% bandwidth at 2GHz

-MIMO Diversity gain central to improved efficiency

-2 logical ports; Polarization diversity utilized (Eh and

Ev received)

-12 physical ports (spatial diversity)

-Unique 360azimuth plane beam forming capabilities

-Elevation up and down tilt beam steering capabillities

Huawei MIMO Base Station Example


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Horizontal Element

4 printed arc-dipoles, centrally fed

Printed stack up and parasitic tuning elements used to obtaingood compromise between size and bandwidth (~27%)

Horizontal (top)

Vertical (bottom)


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Vertical Element

Vertical (top)

Horizontal (bottom)

Small ground monopole

Planar width increases bandwidth


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Obtained Return Loss

Broadband impedance matching obtained, while maintaining compact antennaconfiguration


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Array Design and Considerations

Both horizontal and vertical elements can produce one vertical polarized

omni-directional OR one vertical polarized sector radiation pattern

Spacing between horizontal elements a challenge, grating lobes for array

Top and bottom ground plates introduce phased reflections to mitigate; acts as

a small ground for vertical monopole elements


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Summary 5G Antenna Device design will require high efficiency devices at

frequencies approaching mm wave

CST Array Simulation Workflows provide smooth design process for

large and small finite arrays

Antenna Magus provides Antenna and Array synthesis for rapid

design exploration

System level simulation increasingly important for antennaperformance


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Thank you

COMCAS 2015Advanced Wireless Technologiesby ROHDE&SCHWARZ

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02 Simulation of 5G Antenna Design CST