CHAFF 6.2.11

15.2. Example 2

In this example the BistaticRCS with a sweep on frequency from 3 GHz to 5 GHz with 3 steps over MoM of spherical chaff is calculated.

Step 1

Let's create a Chaff Project. Start newFASANT if it's not already open, then go to File > New, and select a Chaff project.

New Projects command

Module selection box

Step 2

Let's start creating an Spherical Chaff. Go to Chaff > Spherical Chaff and set the values to the following:

  • Center: X=0, Y=0, Z=0.
  • Radius: R=0.5
  • Number of dipoles: 300
  • Radius: 3E-4
  • Max. Length: 1,5E-2
  • Min. Length: 1,5E-2

Spherical Dipole Chaff Menu option

Spherical Chaff parameters and visualization

Step 3

Let's set the simulation parameters so that a frequency sweep is made. Click on Simulation → Parameters. Then enable Sweep by pressing "Enable Sweep" and set the simulation to make a sweep starting on 3 GHz, up to 5 GHz taking 3 samples, as shown in the following figure. Press Save when done.

Simulation Parameters command

Simulation Parameters panel

Step 4

Then, the solver settings will be set. Select Solver → Parameters and set the values to the following:

  • Solver Method: Method of Moments.
  • Conductor Losses: 0 Ω/m.
  • Relative Error: 0.01.
  • Maximum Number of Iterations: 5000.

Solver Parameters command

Solver Parameters panel

Step 5

Let's change the RCS Type. Select RCS → Parameters. Set the RCS type to Bistatic and leave all other parameters as they are by default.

RCS Parameters command

RCS Parameters panel

Step 6

Let's define some far field observation points. Select Output → Observation Directions. Create a phi cut by pressing Add under the Phi Cuts section, and the modify the values in the table. Set the sweeping values as:

  • Phi cut: 0.0º
  • Initial theta: 0.0º
  • Increment: 10.0º
  • Samples: 19

Final theta value should be 180º. Press Save when you are done.

Observation Directions command

Observation Directions panel

Step 7

Select Output → Show 3D Diagram.

Show 3D Diagram option

Since 3D Diagrams increase the time required to simulate the project, you'll be asked to confirm your selection. Press Yes to do so.

Show 3D Diagram question

Step 8

The case has to be meshed before calculating it. Select "Meshing →Create Mesh" and set the number of planar and curved surfaces divisions to 10. This is a small project, so the default settings for processors can be left. Click on Mesh to mesh the example.

Meshing Parameters command

Meshing Parameters panel

Step 9

Then, select Calculate → Execute. Set the number of processors to the better value as available for your computer resources, and press Execute for simulating the project. The operation will take a while since multiple frequencies have been selected and a 3D Diagram calculation has been requested.

Execute Parameters command

Execute Parameters panel

Execute Information panel

Step 10

When the simulation finishes, we can show results. Click on Show Results → Far Field → View Cuts, to show the RCS graphic.

Far Field View Cuts command

Far Filed RCS Graphic

Step 11

Click on Show Results → Far Field → View Text Files, to show the RCS data file.

Far Field View Text File command


Select the frequency to show and click on OK.

Far Field Text File selection

Result Text File visualization

Step 12

Click on Show Result → RCS Diagram → View RCS 3D to load the 3D representation of the measurements.

View 3D RCS command

View 3D RCS

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