[SI-LIST] Re: Dielectric constant for FR4 at above 1Ghz frequency

  • From: "Papa November" <papanovember3@xxxxxxxxxxx>
  • To: si-list@xxxxxxxxxxxxx
  • Date: Thu, 27 Nov 2003 12:40:05 -0500


Hi

I am a newbie to SI. I have started learning HFSS recently. Here is my 
problem;

I tried to simulate a 2 trace transmission on a pcb. I created two models. 
One is 10 cm long and the other is 1 cm long. All other dimensions are 
identical.

I am getting a S11 (dB) curve against frequency with bumps for the long line 
but a continually increasing curve for the short line. Why is this 
difference?, Which one is more accurate? Can anyone suggest a way to cascade 
10 if the small model S parameters to compare it with the long line

0dB|
|
|             ****                  ****
|          *         *              *      *
|        *              *          *          *
|      *                 *       *              *       *
|     *            *    *                *     *
|    *               * *                   *  *
|   *                  *                     *
| *
|*          This is for 10 cm line
|
___________________________________________________________(f)
0                                         10 GHz

0dB|
|
|                     **** ************
|                *
|            *
|        *
|      *
|    *
|*          This is for 1 cm line
|
___________________________________________________________(f)
0                                       10 GHz



Thanks in advance.

PN

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