Re: [SI-LIST] : Total Conductive and dielectric Losses for a micr ostrip trace

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From: WAUGH,RAY (A-SanJose,ex1) (ray_waugh@agilent.com)
Date: Thu Mar 01 2001 - 15:31:38 PST


You can use Martin Schneider's equation to compute dielectric losses (see
attached file, taken from my 1999 seminar).

I think your value of tan delta (0.010) is a bit optimistic. In many cases,
manufacturer's data are optimistic, or taken at 1 MHz (where you are not).

Ray
---------------------------------------------------
   Raymond W. Waugh - WSD Applications
   E-mail: ray_waugh@agilent.com
           Wireless Semiconductor Division
           39201 Cherry Street, MS NK20
           Newark, California 94560
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-----Original Message-----
From: Denomme, Paul S. <Paul.Denomme@viasystems.com>
To: si-list@silab.eng.sun.com <si-list@silab.eng.sun.com>
Date: Thursday, March 01, 2001 10:34 AM
Subject: [SI-LIST] : Total Conductive and dielectric Losses for a microstrip
trace

I am currently working on a job and have a microstrip trace on
GETEK. The trace width is 33 mils 1/2 oz., running at 1GHz, 75 ohms, Dk of
3.9, and Loss tangent of .01. I am trying to calculate the total conductive
loss and the total dielectric losses for this microstrip case. For
conductive losses I obtained 0.189dB/M which seems correct to me. I
obtained this result from Ansoft 2D analyzer. I am also trying to determine
the dielectric losses for this trace but I am not sure if I can use a
formula for this calculation or not. The formula for dielectric loss I have
is

Ad=(27.3*SQR(Er)*LossTangent)/Wavelength

The Ansoft software gave me an effective Dk of 2.88 which is .74 of the
Dk=3.9. I am thinking that I could use the .74*Losstangent as the effective
loss tangent and
plug in the effective dielectric constant and the effective loss tangent
into the above equation to get the dielectric losses. Can anyone tell me if
I am way off base on this one? or am I right on the money?

I would appreciate any feedback.

Regards,

Paul S. Denomme
paul.denomme@viasystems.com

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