# UWB-Antennas Simulation with HFSS - RF Cafe Forums

 The original RF Cafe Forums were shut down in late 2012 due to maintenance issues - primarily having to spend time purging garbage posts from the board. At some point I might start the RF Cafe Forums again if the phpBB software gets better at filtering spam. Below are the old forum threads, including responses to the original posts. -- Amateur Radio -- Anecdotes, Gripes & Humor-- Antennas-- CAE, CAD, & Software -- Circuits & Components-- Employment & Interviews -- Miscellany-- Swap Shop-- Systems-- Test & Measurement -- Webmaster

pashmineh
 Post subject: UWB-Antennas Simulation with HFSS Posted: Sun Mar 25, 2007 11:07 pm
 Lieutenant

Joined: Sun Mar 25, 2007 10:55 pm
Posts: 1
Location: Hannover/Germany
Hello,

I research about uwb-antennas. The only simulation tools that I have, are "HFSS and Matlab".

With HFSS I can simulate only in frequency domain but I need to study the output signal and other parameters in time domain.

My problem is my results are in frecuency domain. How can I get it in time domain?

I will be glad for any tipps.

Thanks.

nubbage
 Post subject: Posted: Mon Mar 26, 2007 5:29 am
 General

Joined: Fri Feb 17, 2006 12:07 pm
Posts: 218
Location: London UK
Sounds like a case for Fast Fourier Transformer.
You could sample the amplitude and phase S21 with say 255 points (the frequency domain "spectrum"), then multiply these by the equally-spaced spectral lines in the frequency spectrum of the input pulse. You then do an FFT number on them with something like MATHCAD. That gives you the time domain or pulse output.
I wrote a MATHCAD routine to do this for a pulse stream entering a twisted pair lossy cable, knowing the frequency dispersion of the cable loss characteristic. First I derived the frequency spectrum of the input pulse stream using the Fourier Transformer in MATHCAD. Multiplying each spectrum line of the input pulse spectrum by the corresponding loss value for that line gave the output spectrum Inverting the frequency domain using the Inverse FFT in MATHCAD I got the output time domain pulse shape showing characteristic pulse distortion (slow rise and fall time edges, sloping flat top, and ringing).

Kim35
 Post subject: Posted: Mon Mar 26, 2007 10:17 pm
 Lieutenant

Joined: Mon Mar 26, 2007 10:14 pm
Posts: 1
 Hi Pashmineh,i work with CSt. It is very good for simulation.Kim

Posted  11/12/2012