[SI-LIST] Re: Equations for creating twisted pair transmission lines?
- From: Juliusz Poltz <jpoltz@xxxxxxxxx>
- To: scott@xxxxxxxxxxxxx, tom_cip_11551@xxxxxxxxxxx
- Date: Wed, 04 Aug 2004 19:09:31 -0600
Hi Tom, Russell and Scott,
We actually have been modeling 4 pair cables, each with different twist
rates, bundle-lay and shields and correlating it with measurement data for
the last 4 years. Although just recently we started looking into tolerance
and manufacturing variations, we presented papers with our customers and
published some of the correlation data based on ideal manufacturing
conditions at the International Wire and Cable Symposium (IWCS 2000-2004).
Automated creation of the geometrical model that is physically similar to
the cable was difficult - but doable. Simulation results of Characteristic
Impedance, speed of propagation, attenuation, NEXT, FEXT and return loss
match the measurement data very well - if the manufacturing process is well
controlled. Although the software calculates S-parameters through chain
parameters it also allows the user to create Spice models (including
w-models).
Best regards
Juliusz Poltz" <jpoltz@xxxxxxxxx>
*****************************************************
OptEM Engineering Inc. Ph: (403) 289-0499
Suite 453 Fax: (403) 282-1238
3553 - 31st Street N.W. Web page: www.optem.com
Calgary, AB Canada T2L 2K7
*****************************************************
----- Original Message -----
From: "Scott McMorrow" <scott@xxxxxxxxxxxxx>
To: <tom_cip_11551@xxxxxxxxxxx>
Cc: <si-list@xxxxxxxxxxxxx>
Sent: Wednesday, August 04, 2004 1:00 PM
Subject: [SI-LIST] Re: Equations for creating twisted pair transmission
lines?
> Tom
>
> As Russell has stated, there is pretty much no way to create a twisted
> pair model from EM field solvers that will correlate with measurement.
> There are so many variations in the manufacture of cable and repetitive
> variations due to the process, that it truly takes measurement to
> determine the actual cable behavior. in our work we have used VNA and
> TDR measurment based modeling approaches to create cable models. I
> would suggest an approach using a TDR and TDA Systems iConnect, or an
> approach using a VNA with a sweep range from the 100 kHz to 1 GHz range
> and s-parameter modeling. (HSPICE now does a reasonably good job of
> using Touchstone S-parameters in time domain simulation ... although it
> is slow)
>
> regards,
>
> scott
>
> --
> Scott McMorrow
> Teraspeed Consulting Group LLC
> 121 North River Drive
> Narragansett, RI 02882
> (401) 284-1827 Business
> (401) 284-1840 Fax
> (503) 750-6481 Cellular
> http://www.teraspeed.com
>
> Teraspeed is the registered service mark of
> Teraspeed Consulting Group LLC
>
>
>
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