Specification of list of frequencies for time domain approximate sinc signal

Altair Forum User
Altair Forum User
Altair Employee
edited October 2020 in Community Q&A

Hi,

 

I wish to provide list of discrete points in Solution frequency in CADFEKO for the purpose of specifying time-domain sinc signal in POSTFEKO. 

  1. When I specify Single frequency,  357989411_Screenshotfrom2019-01-0310-22-18.png.9361473f064a8e018ebc8ff20f3dee82.png, I understand that solution is obtained for this frequency only. In POSTFEKO, ideally a time-signal can be constructed, such as cosine or sine, with exact frequency. Is it correct?
  2. FEKO user manual mentions following about frequency specification:941171076_Screenshotfrom2019-01-0310-30-36.png.c18e7ba2ede63dc4fc6b27e9bb6f5110.png 

I wish to specify List of discrete points that construct a specific time-signal in POSTFEKO. The time signal is a sinc function. Can it be defined mathematically in POSTFEKO? Here I limited sinc to two side-lobes only.

SincFunction.jpeg.3324de7198fa72622fd02a404de17700.jpeg

Overall time duration of signal is 290 μs. How to decompose above signal to: 1. cos() signal for central lobe, and 2. two sin()/cos() functions for negative side-lobes in POSTFEKO? Can frequency of these individual functions be specified as List of discrete points?

 

Thanks,

FieldForcer

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Answers

  • mvogel
    mvogel
    Altair Employee

    In CADFEKO, where you set up the simulation, you should just specify a range of frequencies that is wide enough to represent the time-domain signal later. Don't worry yet about specific frequencies; only make sure you have a proper minimum frequency, maximum frequency and a large-enough number of frequencies to see a reasonable plot of the frequency-domain behavior.

    In POSTFEKO, you can define the time-domain signal mathematically or import a text file with time-domain samples. All the calculations needed for the time-domain results will be done in POSTFEKO.

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