Design, Optimization, and Integration of Antenna Arrays for Next … · 2019-10-08 · Design,...

1© 2019 The MathWorks, Inc.

Design, Optimization, and Integration of Antenna Arrays

for Next-Generation Communications Systems

Giorgia Zucchelli – MathWorks - Product Marketing RF & Mixed Signal

2

DSP

Algorithms

beamforming, beamsteering, MIMO

N

Mixed-Signal ICs

continuous & discrete time

ADC

Waveforms

standard compliant, spectrum and time

DAC

TX

RX

LNA

PA

N

RF Transceivers

frequency dependency, non-linearity, noise, mismatches

Antennas

elements, coupling, edge effects

Channels

interference, clutter, noise

Vision: Model and Simulate Wireless Systems from Bits to Antenna

(and Back)

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Example: Architecture for Hybrid Beamforming

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Example: Architecture for Hybrid Beamforming

Transmitter and receiver relative position (Az, El)

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Example: Architecture for Hybrid Beamforming

RF transmitter

Antenna array 4x8

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Example: Architecture for Hybrid Beamforming

Elevation:

RF beamforming

Azimuth:

Digital beamforming

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Example: Architecture for Hybrid Beamforming

• Thermal noise

• Phase noise

• Image rejection

• Channel selection

• Non-linearity

• Antenna array S-parameters

RF transmitter subarray

Multi-stage up-conversion

8

Example: Architecture for Hybrid Beamforming

RF (ideal) receiver + ADC + AGC

2 orthogonal antenna arrays 1x4

Estimation of angle of arrival (Az, El)

• Dynamic range

• Noise

• Quantization

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Example: Architecture for Hybrid Beamforming

Baseband transmitter

Baseband receiver

Carrier recovery

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Example: Architecture for Hybrid Beamforming

Transmitter and receiver relative position (Az, El)

RF transmitter

Antenna array 4x8

Digital + RF beamforming

RF (ideal) receiver + ADC + AGC

2x Antenna arrays 1x4

Estimation of direction of arrival (Az, El)

Baseband transmitter

Baseband receiver

Carrier recovery

5x

11

Design and Analyze Antenna and Arrays

Without Being an EM Expert

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Antenna and Array Design, Analysis, and Installation

▪ Library of parameterized antenna and array elements

▪ Full wave Methods of Moments solver employed for ports, fields and surface analysis

▪ Antenna installation using hybrid MOM + Physical Optics solver

▪ Antenna fabrication with Gerber file generation

13

Antenna Design – Where To Start?

Antenna Designer App

▪ Select an antenna based on the desired specifications

▪ Design the antenna at the operating frequency

▪ Visualize results and iterate on antenna geometrical properties

▪ Generates MATLAB scripts for automation

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Antenna Catalog: Readily Available Parametrized Geometries (>70)Dipole and Loop

Monopole

Patch Spiral Fractal

Backing and Enclosure

Slot and helix

Aperture

15

What if my Antenna is Mounted on a Dielectric Substrate?

▪ Define Dielectric properties:

▪ Use the dielectric catalogue listing existing materials

▪ Define your own dielectric material

Dielectric Relative permittivity Loss Tangent

Air 1 0

Other >1 (typically <10) >0 (typically ~1e-3)

“metal” antenna

(ideal conductor)

Free space (isolation)

Dielectric substrate

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Increasing the Efficiency of the Antenna Design Workflow

Modelling the dielectric substrate can slow down analysis time

▪ Use antennas in free space for first-cut design

▪ Use parallel computing to speed up design space exploration

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What About Multi-Layered Dielectric Structures?

Suitable for low cost applications requiring high antenna integration

▪ Design printed antennas with pcbStack

▪ Add arbitrary dielectric and metal layers

▪ Define vias and feed structures

p = pcbStack;

p.BoardShape = b;

p.BoardThickness = 3e-3;

p.Layers = {ant,d1,d2,b};

p.FeedLocations = [0.02 0.05 1 4;0.02 -0.05 1 4];

p.FeedDiameter = 1e-3;

p.ViaLocations = [-6e-3 -0.046 1 4;-10e-3 0.042 1 4];

p.ViaDiameter = 1e-3;

Metal and dielectric layers

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Antenna Fabrication with Gerber File Generation

▪ Antenna fabrication in 4 steps:

1. Design your planar antenna / antenna array using pcbStack

2. Choose the manufacturing service

3. Choose the connector type and location

4. Generate Gerber files for fabrication

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Full Wave Antenna Array Design and Analysis

▪ Design an antenna element resonant at the

desired frequency

p = design(patchMicrostrip, 66e9);

▪ Space the elements of an array to minimize

coupling and grating lobes

l = design(linearArray, 66e9, p);

pattern(p, 66e9);

Isolated element

pattern(l, 66e9);

Full array

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Compute the Embedded Element Radiation Pattern

▪ Compute the pattern of the embedded element to take into account proximity and edge effects

pattern(l,66e9,...

'ElementNumber’,1);

Embedded element #1 Embedded element #2 Embedded element #4

pattern(l,66e9,...

'ElementNumber’,2);

pattern(l,66e9,...

'ElementNumber’,4);

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Speed Up Antenna Design with Surrogate Optimization

▪ Use on optimization problems that are expensive to evaluate

– Simulations, differential equations

– Uses fewer function evaluations than other Global Optimization solvers

– Does not rely on gradients: works on smooth and nonsmooth problems

Search for

Minimum

Construct

Surrogate

Reset

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Integrate Antenna Arrays and Phased-Array Algorithms

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Phased Array Algorithms

▪ Beamforming: narrowband and broadband

– Conventional, MVDR (Capon), LCMV, Frost, time delay, time delay LCMV, subband phase

shift, generalized sidelobe canceler, etc

▪ Direction of arrival estimation

– Sum and difference monopulse, Beamscan, MVDR (Capon), ESPRIT, Root MUSIC, etc

▪ Space-time adaptive processing

– Displaced phase center array (DPCA), adaptive DPCA (ADPCA), Sample matrix inversion

(SMI) , angle-doppler response, etc

S

t1

t2Signal

Wavefront

Steering

StageAligned

Signals

Enhanced

Signal

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Combine Antenna Design and Phased Array Algorithms

▪ Need to separately control the excitation to each radiating element

– Amplitude, phase, delay

▪ Use pattern superposition of the individual elements to compute the array pattern

...

% Import antenna element in Phased Array

p = design(patchMicrostrip, 66e9);

u = phased.ULA;

u.Element = p;

Antenna element

Phased Array System Toolbox array

Complex radiation pattern

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Blue = Full wave

Red = Pattern superposition

What if you Need to Take into Account …

▪ Coupling effects in between antenna elements?

▪ Edge effects?

Is pattern superposition of the isolated element sufficient?

Full wave analysisIsolated element

pattern superposition

Comparison

Azimuth Elevation

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Blue = Full wave

Red = Pattern superposition

Estimate Coupling Effects with the Embedded Element Pattern

▪ Compute the pattern of the embedded element to take into account proximity and edge effects

▪ Apply pattern superposition to the embedded element patterns

Embedded element

pattern superposition

Comparison

Azimuth = 0 deg Azimuth = 90 degFull wave analysis

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Modelling the Array Radiation Pattern in Practice

Are the antenna elements spaced far apart?

Mid

Compute the pattern for the

central and the edge (corner)

element embedded in the array

Compute the isolated

element pattern and apply

pattern superpositionWhat is the size of the array?

Small

Compute the pattern for

each element embedded

in the array

Heterogeneous array

Validate (when possible)

with full EM simulation

Ho

mo

ge

no

us a

rra

y

Large

Compute the pattern for the

central element with the

infinite array approach

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Integrate Antenna Arrays, Phased-Array Algorithms, and

RF Transceivers

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RF System Simulation Must Be Fast

▪ Integrate control, calibration, and signal processing (phased-array) algorithms

▪ Simulate non-linear effects, spectral regrowth, noise

▪ Take into account the effects of interfering signals, blockers, spurs

Radio Frequency

signals

Small simulation

time-step

Long simulation

runsNon-linear effects

Interfering signals

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Circuit Envelope to Trade-off Fidelity and Speed

Modeling fidelity

Sim

ula

tion

sp

ee

d Equivalent Baseband

CarrierfreqS

pe

ctr

um

Circuit Envelope

Carrier 1freq

Sp

ectr

um

Carrier 2DCTrue Pass-Band

freqSp

ectr

um

33

Circuit

Envelope

Multi-Carrier Envelope Simulation

… MHz …GHz … fc1

Specify the harmonic order

0

Convert complex envelope modulation to RF signal

Select complex envelope response

fc2

… MHz …GHz …

0 frequency

fc1 fc2fc2-fc1 fc2+fc1

… MHz …GHz …

frequency

fc2+fc1

0

frequency

carriers

harmonic tones

signal envelope

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RF System Simulation Must Be Fast and Accurate

▪ Model RF components at the behavioral level not at the transistor level

▪ Use models characterized by data-sheet specs including impairments, or by measurement data

▪ Take into account impedance mismatches and reflections

▪ Verify that the model behavior is what you expect!

Linear

Non-Linear

System

Tunable

Testbenches

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RF Design – Where To Start?

RF Budget Analyzer App

▪ Implements power/noise/IP3 RF budget analytical computations

▪ Takes into account impedance mismatches

▪ Generates Circuit Envelope models and testbenches

▪ Generates MATLAB scripts for automation and complex scenario analysis

▪ Delivers consistent results between analytical equations and simulation

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Add RF ComponentsExport to RF Blockset

Cascade Budget Analysis

Component

Specifications

RF Cascade

Plot Budget

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RF Budget Analyzer Export to RF Blockset

Measure IP3, IP2, Gain, NF, DC offset

Image Rejection Ratio (I or Q)

Measurement @Low IF (like in the lab)

Circuit Envelope model

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Model and Simulate the Physical Layer of

Wireless Systems from Bits to Antenna

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Antenna and Array Design and Analysis

▪ Library of parameterized antenna and array elements

▪ Full Methods of Moments solver employed for ports, fields and surface analysis

▪ Rapid iteration of different antenna scenarios for radar and communication systems design

▪ Antenna fabrication with Gerber file generation

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Installation on Large Platforms and Propagation Effects

▪ Import STL file to describe your installation platform

▪ Install your antenna / array on the platform and analyze its effects with Physical Optics

▪ Compute coverage and link strength taking into account 3D terrain RF propagation effects

(Longley Rice, TIREM)

▪ Compute Radar Cross Section (RCS)

41

RF (System-Level) Modeling and Design

▪ Model RF systems at high levels of abstraction using measurement data and datasheet specs

▪ Achieve fast system-level simulation with Circuit Envelope solver

▪ Understand non-linear effects and sources of signal distortion

▪ Generate noise using different type of sources and distributions

▪ Model impedance mismatchesCircuit Envelope

Carrier 1freq

Sp

ectr

um

Carrier 2DC

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Mixed-Signal (System-Level) Design and Analysis

▪ Simulate in time-domain using continuous and discrete time signals

▪ Design PLL and ADC using Simulink library of components

– Customizable models for top-down design of typical architectures

– Typical building blocks including analog impairments

– Measurement blocks and testbenches for verification

Measurement testbenches

Phase noise analysis

White-box architectural models

Building blocks including impairments

Open and closed-loop linear analysis

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Waveform Generation

▪ Test with standard-compliant waveforms

▪ Generate all physical channels and signals

▪ Off-the-shelf and full custom waveforms

WLAN

5G

LTE

3GPP

✓ LTE & LTE-Advanced

✓ V2X Sidelink

✓ D2D Sidelink

✓ LTE-M

✓ NB-IoT

✓ 5G New Radio

IEEE 802.11

✓ 802.11ax (draft)

✓ 802.11ad

✓ 802.11ah

✓ 802.11ac

✓ 802.11a/b/g/n

✓ 802.11p/j

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End-To-End Link Level Simulation

▪ Physical layer standard compliant reference models

▪ Evaluate impact of algorithm designs on link performance

▪ Verify algorithm implementation and performance

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DSP

Algorithms

beamforming, beamsteering, MIMO

N

Mixed-Signal ICs

continuous & discrete time

ADC

Waveforms

standard compliant, spectrum and time

DAC

TX

RX

LNA

PA

N

RF Transceivers

frequency dependency, non-linearity, noise, mismatches

Antennas

elements, coupling, edge effects

Channels

interference, clutter, noise

Conclusion: Model and Simulate Wireless Systems from Bits to

Antenna (and Back)

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Use MathWorks for RF System-Level Modeling