farfieldplot cst

MWS can calculate far fields on a spherical polar grid at the desired distance. I wonder wether this is possible with a cartesian grid. What I mean is the following: assume lets say you set up a cartesian grid (over a rectangular area) at 10 meter away from your antenna at 10 GHz. Can MWS calculate the field on this cartesian grid without the need of calculating electric field over such a large volume?

Do you mean integrating the fields over a box, rather than over a sphere ?
Or displaying the calculation on a cartesian grid (postprocessing) ?

P.

I mean the postprocessing.

I'm not sure I understood your scenario but what if you try this :

1. Run your model+Farfield monitors
2. Farfield Plot->Plot Mode=E-field, set Ref. dist =10m
3. Farfield Plot->General->set 2D (Turn off the "use farfield approximation" button)

Hope this helps,
P.

Dear Pushead,
Unfortunately that is not what I need. When you use that feature, CST plots far field still on polar coordinates. But I want MWS to plot the fields on cartesian coordinates (for instance on a x,y plane)

If I remembered correctly, you may use macro to add far field probe, the field position is given in xyz coordinate systems. Of course, you need a big loop to generate one plane.

Regards,

actually, at first thought, I decided to use farfield probes. But the problem with the probes is that they output the fields in whole frequency range. In turn, this gives a huge output and appreciable slow-down of the simulation. If it was possible to set the output frequency for the far field probe, that would definately do the job

Hi Irfan,

I guess this is not direclty possible but you could write a small macro which does this for you. There is a VBA command which aclculates the the farfield at user given points. (Parameter are phi, theta and the radius e.g.)

This should make it possible to get at least the data out of MWS. I acctualy did something similra some time ago (not for a cartesian plane, but just for a simple line)

The problem might be the ploting itself. However, if you have the data you alwaay could use MAtlab or Excel as ploting tool.

F.

Dear RFSimulator,
thank you very much. your comments have always been very valuable and usefull for me.

Dear RFSimulator,
I tried to follow your suggestion. I attempted to code a simple VBA script. But somehow the scripts gives and execution error.

' *FFonLine

' !!! Do not change the line above !!!



Sub Main ()
With FarfieldPlot
.SetPlotMode "efield"
.SetScaleLinear "True"
End With

Dim X As Double
Dim Y As Double
Dim Z As Double
Dim i As Integer
Dim Phi As Double
Dim Theta As Double
Dim R As Double
Dim M As Double
Dim DeltaX As Double

For i = 1 To 101
X=-50+(i-1)*DeltaX
Y=0
Z=200
R=Sqr(X^2+Y^2+Z^2)
M=Z/R
Theta=Atn(Sqr(1 - M^2) / M)*3.141/180
Phi=Atn(Y/X)*3.141/180
Field=FarfieldPlot.CalculatePointNoApprox(Theta,Ph i,R,"Abs","farfield (f=2.5)")
Next i

End Sub

Hi Irfan,

you have to use the "excitation String" after the farfield monitor name.

I guess the corect farfield name would be: "farfield (f=2.4) [1]" where "farfield (f=2.4)" is just the name of the monitor anf the "[1]" is for excitation at port one.

F.

Dear RFSimulator,
Thank you very much for your reply. I have almost completed the macro. I have a final question (i hope it will be a final question ). Is it possible to calculate the radial component of the field. As far as I understood, I can query for the abs, or theta or phi components.If somehow I can retrieve the radial component I will be able to represent the field in terms of all cartesian components.

Added after 14 minutes:

I guess too much coffee too bad for brain. Abs=sqr(phi^2+theta^2+radial^2)? Then I can derive at least the magnitude of the radial component. hmmm, well still not enough for determination of cartesian components of the electric field. I still need the phase of the radial component.