Even in that case, the linear frequency dependence of dielectric loss will
dominate the square root of the frequency of skin losses, so dielectric
losses are the problem much above 2 GHz or so.
ed sayre
============================================
At 07:50 AM 7/26/99 -0700, you wrote:
>"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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>
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| NORTH EAST SYSTEMS ASSOCIATES, INC. |
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| "High Performance Engineering & Design" |
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| NESA, Inc. http://www.nesa.com/ |
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