(From the original file sent to Doug. Due to popular demand)
     
                I'm not a designer but a fabricator in charge of what I
        call "bleeding edge". My experience with RF and FR-4 leads me to 
        believe "you can't get there from here". I've heard of transceivers 
        with multilayer PCBs going to 6 and 8 Ghz, but these guys are pros. 
        Microwave gurus who plug their designs into SPICE for 2-3 wks before 
        they build protos. They acquire the protos and take readings that 
        they plug into their SPICE library. (Constantly gaining real data) 
        If their far off, they tweak and build new protos until they get
        it. The cost of 2 or 3 proto builds still is not as steep as PTFE 
        multilayers.
        Their is new materials out there that are targeted to fill the 
        RF gap between PTFE and FR-4. Starting with a Er of 4.2, One of the 
        PTFE manufacturers now has a rigid mat'l with a low Dk, A new
        continuous laminate manufacturer is making something that looks 
        very promising at Er 3.3. The only problem is that these materials 
        generally are only available in a few thickness'and prepreg is not
        yet available and we have to use something different to bond them 
        together. 
        Let me know if you get some resolution or design related 
        suggestions. I like to stay current with this kind of stuff.
     
        Dave Hoover (Groovy)
     
        (This post has been modified from it's original text so that        
        everybody else can see the direction of the response. <Leaving
        vendors names off>)
______________________________ Forward Header __________________________________
Subject: PC Board Frequency Limits
Author:  [log in to unmask] at SMTPLINK-HADCO 
Date:    5/7/96 10:09 PM
     
     
     
     I would like any responses to be off-line for the following 
     discussion.
     
     Please use the following email address:  [log in to unmask]
     
     I made a simple mathematical model of a stripline, 1 inch trace, on 
     FR-4, nothing out of the ordinary as far as dimensions and found to my 
     surprise a resonant freq at about 800 MHz with a 20 to 40 dB roll-off 
     above 800 MHz
     
     Could someone in the RF/Microwave world of nuts and bolts pc board 
     design tell me what I'm supposed to do at say 10 GHz with regular pc 
     board materials/construction/fabrication???
     
     Thanks in advance, Doug McKean