This is the CST presentation for 5G antenna simulation
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Antennae
Descripción: antenna
Full description
Descrição completa
21.12.2009
Workflow Example Horn Antenna Purpose : Optimize the aperture of the horn antenna such that the gain is maximized at 10 GHz.
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CST MWS - Standa Standard rd Work Workflo flow w
Choose a project template.
Create your model.
parameters + geometry + materials
Define ports.
Set the frequency range.
Specify boundary and symmetry conditions.
Define monitors.
Check the mesh.
Run the simulation.
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Cylindrical Horn Antenna 8 – 12 GHz 1 0.5 0.5
dia=2, rad=1 zlength=2
units: inch waveguide: 1.0 in x 0.5 in x 0.5 in
0.25
aperture radius: 1.0 in, length: 0.25 in shell thickness: 0.01 in (outside) monitors: E-field, H-field & far field at 10 GHz
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Project Template At the beginning choose
“File” -> “New”
For an existing project you may choose
to create a new project.
“File” -> “Select Template”.
The project templates customize the default settings for particular types of applications. 4
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Project Template background material
Antennas should be modeled with vacuum as background material.
PEC is very practical p ractical for closed structures. (e.g. waveguides, connectors, filters)
The project templates customize the default settings for particular types of applications. 5
Change the Units
Define units.
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Horn Antenna – Construction (I)
Define a brick (1.0 x 0.5 x 0.5 in) made of PEC.
Define a cylinder (outer radius: 1.0 in, height: 0.25 in) made of PEC. 7
Pick face. Align the WCS with the face.
Move the WCS by 2.0 inches.
Horn Antenna – Construction (II)
Pick two opposite faces.
Perform a loft.
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Horn Antenna – Construction (III) Perform a Boolean add. Select multiple objects (ctrl or shift + left mouse button).
shell solid: 0.01 in (outside)
Pick two faces.
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Port Definition Pick point inside corner.
Define a waveguide port.
Pick edge.
Define the port on the internal profile. 10
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Set the Frequency Range
Set the frequency range.
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Boundary Conditions and Symmetry Planes
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3D Monitors
Add field monitors for E-field, H-field, and far field at 10 GHz.
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Mesh View (I) mesh properties
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Mesh View (II)
TST at work!
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Transient Solver: Start Simulation The accuracy defines the steadystate monitor. The simulation is finished when the electromagnetic energy in the computational domain falls below this level.
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Analyze 1D Results port signals
S-parameter
energy
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Analyze 2D/3D Results
port information: •
cut-off frequency
•
line impedance
•
propagation constant
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Electric Field at 10 GHz
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Far Field at 10 GHz
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Polar Plot for Far Field at 10 GHz phi=90
phi=0
Create a new folder “Comparison” to compare different 1D results. 21
Parameterization Optimization
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Parame arameter teriza ization tion (I)
r1
outer radius r1 = variable goal: maximize gain
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Parameterization (II)
outer radius r1
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Result Processing Templates (Shift+P) 1D results Define gain(theta) at phi=0.
Postprocessing templates provide a convenient way to calculate calculate derived quantities from simulation results. Each template is evaluated for each solver run. 25
Result Processing Templates (Shift+P) 0D results
Define max of gain(theta).
Read the online help to learn more about the postprocessing in CST MWS. 26
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Result Processing Templates (Shift+P) Alternative solution: The maximum gain can be computed using the “Farfield “Farfield” ” template in “0D Results”.
Define max of gain(theta).
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Parame Parameter ter Swee Sweep p - Settin Settings gs 1
2
3
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Parame Parameter ter Swee Sweep p - Setti Settings ngs Add a S-parameter watch.
The results will be automatically listed in the “Tables” “Tables” folder. folder. 29
Parameter Sweep – Table Results Right click on plot window and select “Table Properties…”.
Choose the result curve for each parameter value with the slider.
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Parameter Sweep – Table Results parameter values
parameter values
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Automatic Optimization
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Automatic Optimization Define the parameter space.
Define the goal function.
Template based postprocessing 0D results can be used to define very complex goal functions. 33
Automatic Optimization Choose the “Classic Powell” optimizer.
Broadband Far Field Analysis How to plot the antenna gain for the complete frequency range?
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Broadb Broadband and Far Field Field Monito Monitors rs
Create a broadband far field monitor from the available monitors.
After monitor definition, start T-solver again! 39
Result Processing Templates (Shift+P) 1D Results
Define maximum value of gain.
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Broadband Far Field Monitors far field 3D pattern
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Broadband Far Field Monitors
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“Tables” -> “1D Results” -> “Broadband gain 3d”
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Co- / Cross Cross-Po -Polar lariza izatio tion n
The co-polarized far field component has the same polarization as the excitation (y-oriented in our case). cas e). The cross-polarized far field component is orthogonal to the co-polarized component and main lobe direction. In order to use different polarizations for fo r transmitting/receiving, an antenna design goal might be to maximize the co-polarized and minimize the cross-polarized component. 44
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Co- / Cross Cross-Po -Polar lariza izatio tion n 1. Select the tab “Axes“. 2. Click “Main lobe/polarization alignment“. 3. Choose the “Ludwig 3“ coordinate system.
polarization vector direction (arbitrary user input possible).
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If “Main lobe ... “ is not selected, the user can enter arbitrary directions for: -polarization plane normal (z„) (= theta axis) -cross-polarized -cross-polarized component (x„) (= phi axis).
Co- / Cross Cross-P -Pola olariz rizati ation on
co-polarized = Ludwig 3 vertical
cross-polarized = Ludwig 3 horizontal
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Co & Cross Polarization Result Templates for Parameter Sweep and Optimization co-polarized= Ludwig 3 vertical
cross-pol. = Ludwig 3 horizontal
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Phase Center Calculation Finding the best location to place the horn inside a parabolic antenna. The best position dish is to match the focal point of the dish with the phase center of the horn.
= y‘z‘ plane = x‘z‘ plane
?
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Check Phase Center Check the phase center by plotting the Ludwig 3 v ertical phase.
Plotting the phase of Ludwig 3 vertical (=dominant component of co-polarized fields) does not result result in a 180° jump of the phase (=color (=color jump) at theta=0.
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Check Phase Center Check the phase center by moving the origin origi n to the phase center.
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See also article (Phase Center comparison with measurements) on www.cst.com www.cst.com.. -> application article ID=256
