design, optimization, and integration of antenna arrays for next … · 2019-10-08 · design,...
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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
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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
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
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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
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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
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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
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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
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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)
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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