Re: [SI-LIST] : Microstrip losses

D. C. Sessions (dc.sessions@vlsi.com)
Mon, 26 Jul 1999 07:50:53 -0700

"WAUGH,RAY (HP-SanJose,ex1)" wrote:
>
> Chris...
>
> Indeed, the dielectric losses dominate in embedded microstrip and in
> stripline, just as they do in conventional microstrip.

That makes sense if your paths are 60 mils wide. For those of us
using 3-5 mil traces skin effect may play a larger part.

> -----Original Message-----
> From: Chris_Heard@ne.3com.com [mailto:Chris_Heard@ne.3com.com]
> Sent: Monday, July 19, 1999 5:23 PM
> To: si-list@silab.eng.sun.com
> Subject: RE: [SI-LIST] : even-odd mode influence
>
> Ray,
>
> You mention that material dominates losses on microstrips, is this no
> longer true with embedded microstrips? Is this statement true with
> stripline constructions as well? I would expect it to be so.
>
> Thanks for sending such excellent information.
>
> Chris Heard
> 3Com Corp
>
> "WAUGH,RAY (HP-SanJose,ex1)" <ray_waugh@am.exch.hp.com> on 07/19/99
> 07:05:05 PM
>
> Please respond to si-list@silab.eng.sun.com
>
> Sent by: "WAUGH,RAY (HP-SanJose,ex1)" <ray_waugh@am.exch.hp.com>
>
> To: "'si-list @silab.eng.sun.com'" <si-list@silab.eng.sun.com>
> cc: (Chris Heard/US/3Com)
> Subject: RE: [SI-LIST] : even-odd mode influence
>
> Steve...
> The measurements I made on FR4 (and three other lower cost materials) were
> made on microstrip lines which were five to eight inches long. What we (my
> colleague Dan Swanson and I) did find is that microstrip line losses are
> dominated by losses in the dielectric (rather than in the copper
> conductors). As a consequence, the loss tends to be a fixed number when
> expressed as dB/wavelength. See the attached PDF file.
> At 10 GHz, an 18 inch FR4 microstrip line is going to be a bit lossy.

-- 
D. C. Sessions
dc.sessions@vlsi.com

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