NEW FASANT
Radome Module
Version 5.7.5.16.06.2014
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Index
1.
GETTING STARTED ..................................................................................................... 4
2.
FILE OPTIONS ............................................................................................................. 5
3.
GEOMETRY OPTIONS................................................................................................. 5
4.
RADOME MENU ........................................................................................................ 6
1.
2.
3.
4.
5.
DEFINITION OF THE INTERFACES............................................................................................................... 6
DEFINITION OF FREQUENCY SELECTIVE SURFACES ON THE INTERFACES ............................................................ 9
ASSIGNING MATERIALS TO THE LAYERS .................................................................................................... 13
TRANSLATION AND ROTATION OF AN EXISTING RADOME ............................................................................ 14
SIMULATION MENU ................................................................................................ 16
1.
2.
SIMULATION PARAMETERS ................................................................................................................... 16
CONFIGURING THE SOLVER ................................................................................................................... 17
6.
ANTENNAS MENU ................................................................................................... 19
7.
OUTPUT MENU........................................................................................................ 20
8.
MESHING MENU...................................................................................................... 20
9.
CALCULATE MENU ................................................................................................... 22
10.
SHOW RESULTS MENU ........................................................................................ 23
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1. Getting Started
This module allows an easy and efficient design of radome structures, as well as analysis of
existing designs. In order to start a project, execute NewFasantand select a Radome project.
Figure 1: Radome module
Figure 2: Project name
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2. File Options
The File menu option allows the user to open existing projects, create new ones, close
projects, execute a batch of previously defined simulations or save the existing project.
Figure 3: File menu
3. Geometry Options
The Geometry menu option can be used to perform a wide number of operations with the
geometric elements of the scene, including:
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Creation of new geometries using existing primitives.
Deletion of existing objects.
Modification of objects using a wide variety of techniques, including the
possibility to create user-defined primitives.
Visualization of properties.
Import/Export geometries.
Management of layers.
For more information please consult the Geometry User Guide.
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Figure 4: Geometrymenu
4. Radome Menu
This menu allows to define the interfaces which will serve to separate the radome layers, as
well as to configure their material characteristics. It will be necessary first to define such
interfaces using previously built surfaces, or to use existing primitives on-the-fly.
Figure 5: Radome menu
1. Definition of the Interfaces
It is important at this point to remark the ordering criteria for the surfaces which will be
selected as interfaces: The inner surface (i.e., the closest to the antenna) will be identified
as the first interface, while the external one will be the last interface. The user must be
aware of this ordering procedure because it will be provided in the radome design process,
as shown in the next figures.
To configure the interfaces, the user must have previously created the corresponding
surfaces, or use primitives included in NewFasant. This interfaces will set the boundaries
between layers, as well as the limits of the radome structure with the outer scene (set by
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the first and the last interface). Therefore the number of layers of the radome will be the
same as the number of interfaces minus 1.
After selecting Define Interface it will be necessary to select each one of them:
Figure 6: Selecting interfaces for the radome
After selecting Primitives, the user can choose between a list of surface types, and after
clicking on Set all the parameters associated to that surface will be requested, as indicated
in the Geometry User Guide:
Figure 7: Primitive options for the interfaces
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Figure 8: Selecting a cylinder as primitive for an interface
On the other hand, the user can select User Defined to indicate that an arbitrary, previously
created surface will be the interface. It will be necessary to click on Select Object. In order
to select the surfaces in the right order (from the inner one to the external surface) it can
be useful to use the Front Object and Back Object options, as indicated in the figure:
Figure 9: Selecting an existing surface
Notice that in the previous figure the selected interface is the internal one, which will be
numbered as interface 1.
After selecting the interface it will be deleted from the scene and treated as a special type
of entity to build the radome. The following message will appear:
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Figure 10: Information message after selecting an interface
The previously described procedure will be followed to include all the interfaces of the
radome.
Note that, due to the technique described above to identify the interfaces for the layers,
it is not required that a layer has the same thickness along all its points, since this
thickness can change point to point, as defined by the separation between its boundary
interfaces.
2. Definition of Frequency Selective Surfaces on the Interfaces
Once all the interfaces have been defined the user can click on Advanced Options in order
to define Frequency Selective Surfaces placed over any of these interfaces (if desired):
Figure 11: Advanced Options menu
The Free Geometry option deletes the information of the interface and restores the surface
used to generate that interface. It can be used if the wrong surface was selected by
mistake.
Selecting Enable allows the user to define a FSS located over the interface, after which the
user can indicate if it is going to contain inductive or capacitive cells, and define them
clicking on Define Cell.
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Figure 12: Cell definition window
Clicking on Cell->Edit the user will define the parameters of the basic cell (number of
divisions per wavelength and the planar spatial periods), as shown in the following figure:
Figure 13: Cell parameters
The FSS defined over any interface will be totally conformed to the original surfaced after
being defined. A mapping algorithm is used for this purpose after the cells are defined.
After selecting the cell parameters the user can click on Geometry (inside the Define FSS
window) in order to introduce the geometry which will be located inside each cell.
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Figure 14: Geometry definition for the FSS
As seen in the previous figure, it is possible to define a user created geometry, imported
from an external file, as well as a number of primitives included by NewFasant. After
selecting one of these primitives it is possible to change the geometrical parameters:
Figure 15: Geometric parameters for a primitive
After selecting the parameters the cell and the geometry are visualized.
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Figure 16: Visualization of the selected cell and geometry
It is possible to click now on Cell->Save&Exit in order to keep the defined FSS configuration
for the current layer.
After all the interfaces have been defined the user can introduce the number of processors
to use in order to synthetize the radome. When this process finishes the user can export
the resulting FSS to an external file if desired.
Figure 17: Selection of the number of processors
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3. Select Materials to the layers
After the previous procedure, the user will be requested to introduce some parameters to
define the material included in each layer.
Figure 18: Definition of materials
It is possible to add new materials to the existing list clicking on New Material, change the
parameters of an existing on clicking on Edit Material or delete a material with Delete
Material. It is also possible to assign a color to each material (by clicking on the “color”
check box) for a better visualization of the radome geometry. After selecting the material
associated to the layer click on Set. After this the message “The material has been added”
will be displayed.
Figure 19: New Material Definition
Note that each substrate is defined by means of its name, relative permittivity (epsilon),
and relative permeability (mu). Epsilon and mu are complex numbers, so a real part and an
imaginary part must be defined. If the material has losses, a negative imaginary part in the
epsilon should be indicated. If the material is lossless, the imaginary part is 0.0. Typically,
the mu value is set to (1.0, 0.0).
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After selecting the materials for the layers of the radome, the resulting geometry will be
visualized.
Figure 20: Visualization of the structure
4. Translation and Rotation of an existing Radome
In order to perform one of these operations with a previously created structure, the user
should click on Radome (see Fig. 6), and choose the operation to be performed. Note that
these options are different from those contained in the Geometry menu because the
radome is a special type of entity, different from the conventional geometric primitives.
After choosing any of these options a window will appear, requesting the base and the end
points for the selected operation.
Figure 21: Translation of the radome
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Figure 22: Result of the translation operation
Figure 23: Rotation of the radome
Figure 24: Result of the rotation operation
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5. Simulation Menu
This menu allows to define the parameters of the simulation for the analysis of the previously
generated radome.
Figure 25: Simulation menu
1. Simulation Parameters
Clicking on Parameters the user can define a frequency sweep for the simulation, as well as the
path of the output pattern file.
Figure 26: Simulation parameters
It is possible to select 3 simulation types. After choosing Monostatic RCS or Bistatic RCS the
Source button will be enabled in order to allow the user to configure the incident plane waves.
The direction of the impinging plane wave can only be defined for the Bistatic RCS simulation
type, since for the Monostatic type it will depend on the observation directions:
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Figure 27: Source definition for Monostatic RCS
Figure 28: Source definition for Bistatic RCS
2. Configuring the Solver
Clicking on Solver it is possible to define the simulation method to consider for the
computation of the results. There are three possible choices:
Figure 29: Solveroptions
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Hybrid MoM-PO: The antenna is computed using the Method of Moments to
obtain rigorously the fields radiated over the radome, and these fields are
processed to obtain the final results using the Physical Optics approach over the
radome. No interactions between antenna and radome or between different
parts of the radome are computed. This is the fastest option, suitable for
radomes which are very transparent to electromagnetic waves.
Hybrid MoM-MoM: The antenna is computed using the Method of Moments to
obtain rigorously the fields radiated over the radome, and these fields are
processed to obtain the final results using the Method of Moments over the
radome. No interactions between antenna and radome are computed, but
interactions between different parts of the radome are considered. This option is
a compromise of speed and accuracy.
MoM:All the geometry, including antenna and radome, is computed using a fullwave approach and including all possible interactions. This is the most accurate
option and the radome does not need to be transparent to the electromagnetic
waves to obtain good results.
The user can also change the default value for the maximum relative error allowed in the
solution process. Lower errors will yield more accurate results (using either option indicated
above), but longer processing time.
Under Options menu the user can choose to use a preconditioner in the simulation, which is a
highly recommended choice.
Figure 30: Optionsmenu
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6. Antennas Menu
This menu allows to define the antennas to be used with the previously defined radome
structure. The user can choose among a set of short dipoles, a patter field of an antenna
(which, for example, can be the result of a previous simulation using NewFasant for the
antenna alone), a primitive antenna or a user defined antenna saved in other project.
Figure 31: Antennas menu
NewFasant offers a wide range of primitive antenna types, each of them fully parametrizedto
satisfy the user’s needs. For more information see the Antenna User Guide. Note that it is also
very easy to create 2D or 3D arrays from existing antennas using Geometry->Create Geometry>3D Rectangular Array. With the “Import Antenna From Project” it is possible to use a
previously defined antenna as the source for the current radome project.
Figure 32: Example radome with antenna
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7. Output Menu
The user can define here the results to be obtained after the simulation. It is possible to define
an arbitrary number of cuts in the theta or phi spherical coordinates.
Figure 33: Angular sweepconfiguration
8. Meshing Menu
This menu allows to obtain the mesh of the previously generated geometry, and this is
mandatory for the simulation process. For a complete description of all the options included
with the meshed the user can see the Meshing User Guide.
Figure 34: Meshing menú
After selecting Create and Visualize mesh it is posible to select the number of divisions per
wavelength and set the working frequency for the meshing process, as well as the number of
processors to be used.
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Figure 35: Meshing window
When the meshing process finishes it will be possible to visualize the mesh, together with
some information about the number of nodes and elements.
Figure 36: Resulting Mesh
Note that depending on the solver type selected by the user in the Simulation menu some
parts of the geometry will not be meshed (for the hybrid MoM-PO option), or two meshes
will be generated instead of one (for the hybrid MoM-MoM option).
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9. Calculate Menu
This menu allows the user to run the analysis, using the meshed geometry and the simulation
and output options configured. After selecting Start the user can choose the number of
processors to be used in parallel for the simulation.
Figure 37: Launching the simulation
While the execution is in progress, some data will be displayed. This window will automatically
disappear when the simulation process finishes.
Figure 38: Informationwindow
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10. Show Results Menu
This menu allows the visualization of the results of the simulation. For a detailed explanation
of all the different options see the Results Visualization User Guide.
Figure 39: Show Results menu
Choosing between the different options available in this menu the user can plot the angular
cuts defined in the Output menu, visualize the text file results, a 3D view of the resulting
radiation pattern (or RCS results, depending on the source chosen), the current distribution
over the geometry or its charge distribution. Each one of these options has, in turn, a number
of possible configurations to offer the user an accurate control of the kind and format of the
data to be shown.
Figure 40: Cutvisualizationconfiguration
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Figure 41: Radiation pattern over an angular cut
The user can configure al well a number of options over an existing cut clicking on the blue
triangle on the top right corner:
Figure 42: Extended options
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Figure 43: Text file results options
Figure 44: Plain text results
The 3D radiation pattern, as well as the current and charge density results, display 3D views of
the geometry that can be rotated or zoomed freely by the user. It is also possible the filter the
values of the current or charge density and retain only those included inside a predefined
range (using the Filter option). This option can be very useful to study problems with a large
dynamic range in the results.
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Figure 45: 3D radiation pattern results
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Figure 46: Current density results
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Figure 47: Filtered Current density results
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Figure 48: Filtered Current density results
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Figure 49: Chargedensityresults
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