A recent GETEC presentation showed the following information for the range 
of 800 Mhz to 2 Ghz:
GETEC  3.8
BT/epoxy 4.0
Teflon 2.2-3.5
FR4 4.2
Our local rep covering the Arizona area  for the General Electric materials 
is Jeannie Newhart.  Her e mail address is [log in to unmask]
 ----------
From: [log in to unmask]
To: [log in to unmask]
Subject: Re: Fabrication
Date: Wednesday, September 04, 1996 7:03PM

        I have seen data to suggest the difference between 1 Mhz to 1 Ghz 
     is ~10%. Like standard FR-4 is ~4.5 @ 1 Mhz and ~4.1 @ 1 Ghz. I 
     haven't seen values at 2 Ghz. Some materials have a flatter response 
     across a larger (BW) range of frequencies. This means that they have 
     less electrical performance variation(degradation) from say 1 Mhz to 1 
     Ghz. Some of these materials are Getek, BT, Cyanate Ester, and 
     alternative glass fiber styles (random aramids). Remember there is a 
     cost associated with the higher performance materials.
        One thing I do know is that not all material manufacturers have ran
     these Er tests at different frequencies. The exotic material suppliers
     have, but not all the standard FR-4 makers. We (fabricators) have 
     constantly been asked this question by our customers and have 
     requested this type of testing from our material suppliers. Few have
     responded. In order for their materials to even be considered for an
     RF design they need to at least do their homework. The other materials
     provide a "slight edge" electrical performance wise and those 
     suppliers have targeted this market with their Er and Df results at 
     various frequencies (as you've requested). Wake up call!
        Groovy


______________________________ Reply Separator
_________________________________
Subject: Fabrication
Author:  [log in to unmask] at SMTPLINK-HADCO
Date:    9/4/96 6:05 PM


From: Scott B. Westheimer
Date: September 5,1996

I am looking for information about the Dk of material measured at 1 mhrtz
and measured at 1 and 2 ghrtz. What would be the expected change? Does
anyone have an article that they could send me are direct me too? Are any
of you PCB end users requiring that boards be measured at 1 to 2 ghrtz?

Thanks

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