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CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Microstrip Patch Array Design
Workflow Using CST MICROWAVE STUDIO®
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Introduction
Single element Array factor
design
optimization full model
feeding network
Antenna array
TBP optimization
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
1. Design a single patch element
Resonant frequency, (gain)
2. Postprocessing optimization of feeding
coefficients and spacing (Array Factor)
Gain, sidelobe level
3. Design and optimize a feeding network
S11, bandwidth, gain, sidelobe level
Design Procedure
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
1. Design a Single Patch Element
ABS Cover
RO4350
Aluminium
Stackup
Reference
plane
pW
pW
msW
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Microstrip Width
msW
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Create the Waveguide Port
Macros -> Solver -> Port ->
Calculate port extension coefficient
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Symmetry Settings
Magnetic symmetry
in YZ plane
Open (add space)
boundaries are used
to estimate backlobes
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Mesh Settings (1/2)
At least 2 - 4 cells per strip width
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Mesh Settings (2/2)
2 cells per substrate height
At least 2 cells per air gap
ABS Cover
RO4350
Aluminium
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Patch Width for Resonance at 5.5GHz
pW=19.5mm
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Electric Field at 5.5GHz
Radiation
Travelling wave
Standing wave
ABS Radome
(not shown)
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Single Patch Farfield Pattern
Discrete face port
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
1. Design a single patch element
Resonant frequency, (gain)
2. Postprocessing optimization of feeding
coefficients and spacing (Array Factor)
• Gain, sidelobe level
3. Design and optimize a feeding network
S11, bandwidth, gain, sidelobe level
Design Procedure
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Array Factor
),(),(),( AFFF elementarray Array Pattern Multiplication
(for 5 patch antennas)
Assumptions: identical elements with no coupling.
= x
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Farfield Pattern for Uniform Array
phi=90
phi=0
phi=45
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Magnitudes for Optimal Array
mag1 mag2
mag1
mag2
mag2
mag2
mag3
mag3
Magnitudes will be optimized in order to minimize sidelobe level
Online demonstration
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Optimize Feeding Coefficients (Optimal Array)
phi=90
phi=0
phi=45
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Optimizer Settings (Optimal Array)
Not necessary to optimize mag3 (mag1, mag2 are relative)
The spacing parameter
was optimized for uniform array
Only TBP results
are evaluated
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Template Based Postproc. Settings
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Arbitrary Array Distribution
No ENTER there
File could contain variables
from CST MWS Parameter List
One TAB there
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Array Factor Approach Validation (Optimal Array)
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Array Wizard Macro
Construct finite array
Update Simultaneous
Excitation
Setup array factor
Combine results
(no Sim.Ex.)
Online demonstration
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Array Construction with Array Wizard
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
1. Design a single patch element
Resonant frequency, (gain)
2. Postprocessing optimization of feeding
coefficients and spacing (Array Factor)
Gain, sidelobe level
3. Design and optimize a feeding network
S11, bandwidth, gain, sidelobe level
Design Procedure
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Farfield – Effects of Housing
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Include ABS Cover
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Effect of Housing on Farfield Pattern
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Effect of Housing on Farfield Pattern
The actual housing effects
mainly the back radiation
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Feeding Network Design
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Compute 16-port S-parameters
Discrete Face port
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
S-Parameter Symmetry Settings
16-port excitation reduced to 4-port
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Design the Feeding Network Using Ideal
Transmission Lines
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Optimize the Feeding Network in DS (Optimal Array)
16 parameters
to be optimized
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Farfield + Feeding Network
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Feeding Network (3D Model)
Curves Trace from Curve… This half is
mirrored
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Symmetry Settings (1/2)
Magnetic
symmetry (YZ plane)
Open (add Space)
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Symmetry Settings (2/2)
Is it possible to use
a symmetry in ZX plane ?
No symmetry in ZX plane:
The microstrip requires magnetic symmetry
however the patches require electric symmetry.
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Mesh Settings (1/2) 2 cells per strip width
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Mesh Settings (2/2)
Influences simulation speed
2 cells per substrate height
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Initial Feeding Network Results
3D optimization is necessary to include couplings
between the feed network and radiating elements.
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Electric Field
Coupling between the line and the patch
Phase delay due
to couplings.
Full wave
3D optimization
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Optimizer Settings (Uniform Array)
13 parameters
to be optimized
Very
effective
for 3D
optimization
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Optimized S-Parameters (Uniform array)
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Optimized Farfield Pattern (Uniform array)
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Start with simple models and add complexity
Post processing optimization of farfield pattern
Array wizard macro for array construction or array
factor settings
3D EM/ Circuit co-simulation (feeding network)
Trust Region Framework optimizer for 3D optimization
GPU acceleration
Key Features for Antenna Array Design
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Divide complex task into smaller ones.
Use best approach at each stage.
Optimize your device.
Shorten your development cycle.
Conclusion
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Thank you!
Any questions?