excitation signal cst

Hello, Can anyone tell me how to input an arbitrary excitation signal in CST? I know that this can be done in XFDTD. Thanks for your attention.

Hi,
You can synthsize your own excitation:
Go to Transient solver -> look at the lower part of the dialog box, you'll see the desired option.
After that you'll have to edit the function using VBA macro language.
Take a look at the manual/help for more details and examples.
Good luck,
P.

Thanks for your attention, Pushhead. But the excitation signal I want to use too complex to be expressed by expressions, and I don't want to approximate it by interpolation. Best Wishes.

Can anyone help?

Can you provide an example of the signal/model, or the pupose of the simulation?
P.

O.C. Pushhead.
In a two antenna system, I want to feed the transmit antenna with a generator signal to see if a specific waveform can be got at the receiver antenna.
specifically, the generator waveform is got by ifft from frequency domain signal, so it is very complicated to be approximated using a polynomial.
Thank you:)p

why don't you try using a lookup table, with interpolation.
also, I don't see any reason for not using polynomials, you can use polyfit on matlab (I think there is also a better instruction that can approximate the function using rational functions but I am not sure of its name). I think for whatever complex the signal is you may get it using a high order enough polynomial.
also note that the accuracy of the signal is limited by the maximum frequency setting in microwave studio

hi, adel, I think you are right, but I think using a lookup table is easier and more straight forward, but how can you know the time step used in the simulation?Thank you for your kindly help.

you can see the solver log file, it includes the timestep, also during the simulation the status message shows the time step

oh, thank you very much.

There are two ways to do this in user defined excitation, depends on what type of signal you have
(1)Use equation in VBA, such as a sine wave or other equation profile.
(2)Use ASCII table file, first column is time, second column is exciation amplititude. This can be anything such you get the data from VNA or TDR. then use CST buildin Macro import the file as the excitation.
CST MWS will interpolation in time step. Hope this help