Building Coaxial transmission line on PCB?

[...]
"werty" <werty@swissinfo.org> wrote in message
news:1171348634.104020.242500@l53g2000cwa.googlegroups.com...
>
> ----------------------------------------------------------
>
>   Boxed !   the wavelength is far greater than
>  your dimensions , thus higher modes can not
>  exist , thus you do NOT need sides .
>     When you reach 10 Ghz , then maybe
>   you need sides in ur boxed "coax" .
>
>   But the big joke , is in the real world ,
>   they use cheap PCB to xmit 2.5 Ghz .
>    No strip line , no microstrip , nada ..
>    It works well , so quit arguing reality .
>
>     BTW , i saw some novice , trying to
>    use juice cans to launch WiFi .
>   He figured the more cans , the more
>    gain .  He had 3 cans , T'd .
>    to divide the  power .
>      Gain is not in cans , its in size of
>    the dish .
>
>     Another book worm said all i needed
>     was $26 for 100 meters of  blah blah
>    coax at 2.5 Ghz ..
>
>      10 times that price !
>      and 1.8" dia  hard line !
>
>     At these wavelengths , its lower loss
>    to  send it TEM  and thru the air ,
>    not thru a coax .
>
>  This is goin to FPGA ?  Do those relics
>   still exist ?!  Oh well , i supose ya gotta
>   try to "protect" your firmware by reinventing
>   the CPU !
>

Que?.
Don't listen to the worms.
Video comes in forms other than digital.




-- 
Posted via a free Usenet account from http://www.teranews.com

On Tue, 13 Feb 2007 18:41:00 +0100, Geronimo Stempovski  
<geronimo.stempovski@arcor.de> wrote:

> Now I'm looking for a diagram like frequency (some MHz to 10 GHz for
> example) versus loss tangent and / or epsilon R for FR4. I only found a  
> poor
> black-and-white copy from 1991 in a paper which I searched with Google. I
> wouldn't have thought it to be so hard to find a graph... Does anybody  
> know
> where I can find that?

Hello,

I am sorry to tell that, but for frequencies of 1 to 10 GHz, FR4 ist not  
the right material, there are other PCB materials which are better for  
high frequencies, take a look here
http://www.andus.de/Leiterplatten/Impedanz/hfmat.htm
They write there that FR4 may be used up to 4 GHz.

Bye

On Wed, 14 Feb 2007 15:36:15 +0100, "Uwe Hercksen"
<hercksen@mew.uni-erlangen.de> wrote:

>On Tue, 13 Feb 2007 18:41:00 +0100, Geronimo Stempovski  
><geronimo.stempovski@arcor.de> wrote:
>
>> Now I'm looking for a diagram like frequency (some MHz to 10 GHz for
>> example) versus loss tangent and / or epsilon R for FR4. I only found a  
>> poor
>> black-and-white copy from 1991 in a paper which I searched with Google. I
>> wouldn't have thought it to be so hard to find a graph... Does anybody  
>> know
>> where I can find that?
>
>Hello,
>
>I am sorry to tell that, but for frequencies of 1 to 10 GHz, FR4 ist not  
>the right material, there are other PCB materials which are better for  
>high frequencies, take a look here
>http://www.andus.de/Leiterplatten/Impedanz/hfmat.htm
>They write there that FR4 may be used up to 4 GHz.
>
>Bye


FR4 can be used at 20 GHz, depending on what you're trying to do.

John

Again, I'm looking for a diagram like frequency (some MHz to 10 GHz for 
example) versus loss tangent and / or epsilon R for FR4 or other usual PCB 
material. I only found a poor black-and-white copy from 1991 in a paper 
which I searched with Google. I wouldn't have thought it to be so hard to 
find a graph but as noone replied to my previous question so far it does 
seem to be hard! :-)

Does anybody know where I can find that?

Regards    Gero 

On Thu, 15 Feb 2007 08:55:05 +0100, "Geronimo Stempovski"
<geronimo.stempovski@arcor.de> wrote:

>Again, I'm looking for a diagram like frequency (some MHz to 10 GHz for 
>example) versus loss tangent and / or epsilon R for FR4 or other usual PCB 
>material. I only found a poor black-and-white copy from 1991 in a paper 
>which I searched with Google. I wouldn't have thought it to be so hard to 
>find a graph but as noone replied to my previous question so far it does 
>seem to be hard! :-)
>
>Does anybody know where I can find that?
>
>Regards    Gero 
>

Google gives lots of hits on stuff like "loss tangent fr4 frequency"

But FR-4 varies a lot, so there's no definitive data.

What are you trying to do?

John

On Wed, 14 Feb 2007 17:10:34 +0100, John Larkin  
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

>
> FR4 can be used at 20 GHz, depending on what you're trying to do.

Hello,

well, if the transmission line is very, very short.....


bye

On Thu, 15 Feb 2007 08:55:05 +0100, Geronimo Stempovski  =

<geronimo.stempovski@arcor.de> wrote:

> Again, I'm looking for a diagram like frequency (some MHz to 10 GHz fo=
r
> example) versus loss tangent and / or epsilon R for FR4 or other usual=
  =

> PCB
> material. I only found a poor black-and-white copy from 1991 in a pape=
r
> which I searched with Google. I wouldn't have thought it to be so hard=
 to
> find a graph but as noone replied to my previous question so far it do=
es
> seem to be hard! :-)

Hello,

look here for FR408
http://www.isola.de/d/ecomaXL/index.php?site=3DISOLA_DE_product_addition=
al_information&sid=3D235&p=3D10

bye

On Thu, 15 Feb 2007 16:15:49 +0100, "Uwe Hercksen"
<hercksen@mew.uni-erlangen.de> wrote:

>On Wed, 14 Feb 2007 17:10:34 +0100, John Larkin  
><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:
>
>>
>> FR4 can be used at 20 GHz, depending on what you're trying to do.
>
>Hello,
>
>well, if the transmission line is very, very short.....
>
>

Exactly.

John

> work.  I can imagine that John J. may well also.  When you're aiming
> at 100+dB isolation among traces, you do have to be pretty careful,
> even at "low" frequencies.
>
> Cheers,
> Tom- Hide quoted text -
>
> - Show quoted text -

______________________________________

 Its all theory .   If its open , the RF will leak
  out .  Like the holes in a MicroWave dish
    ----------------
  10:1 SWR , open lines ,
   and NO radiation .
    -------------------
  Transmission lines repulse , but that
  does NOT mean magnetic fringing
  and sending mag flds everywhere .
    ----------------------

     BTW
 Study  CAT5e Ethernet cable .
          garbage !
  USB cables are much faster .


   I think ppl limit themselves to
 whats avail in PCB , then complain
 when it dont work , but if they'd
 experiment , they'd find the problem
 is using thin PCB .
    Then they limit on putting down
  100 transmission lines per mm .
  You cant learn , unless you experiment.

  you can't choke the dimensions
 and get good results , a transmission
 line needs exact dimensions , or you
 lose .

   In coax for 2.5 Ghz , for example ,
 it WILL have a large diameter and
 the center will have an exact dia and
 ratio ..  No substitutes .

  Sending signals that will be amplified
 use high Z ( ~65 ohms )  and
  sending power needs  low Z .
  These rules can't be bent .
   Thats what you're doin , is bending
   rules ...









.

On Feb 13, 7:51 am, John  Larkin
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> On Tue, 13 Feb 2007 20:46:04 +1300, Jim Granville
>
>
>
>
>
> <no.s...@designtools.maps.co.nz> wrote:
> >werty wrote:
> >> On Feb 12, 2:30 pm, "john jardine" <j...@jjdesigns.fsnet.co.uk> wrote:
>
> >>>"Geronimo Stempovski" <geronimo.stempov...@arcor.de> wrote in message
>
> >>>news:45d04b34$0$27624$9b4e6d93@newsspool2.arcor-online.net...> I think transmitting high-speed signals is very easy when you have a
>
> >>>>360-degree ground reference, round conductors,
> >>>>and no other nearby signals like in coaxial cables. My aim is to design
>
> >>>PCB
>
> >>>>tracks as much like a coaxial cable as
> >>>>possible. Anyone tried this before? Is it possible with regular FR4,
>
> >>>anyway?
>
> >>>>Thanks for your help.
>
> >>>>Gero
>
> >>>Had trouble with crosstalk on a mass of video signals. Cured with a
> >>>multilayer board where each signal was 'boxed in' by ground plane to the
> >>>sides, above and below. Sort of square coax.
>
> >> ----------------------------------------------------------
>
> >>   Boxed !   the wavelength is far greater than
> >>  your dimensions , thus higher modes can not
> >>  exist , thus you do NOT need sides .
> >>     When you reach 10 Ghz , then maybe
> >>   you need sides in ur boxed "coax" .
> ><snip>
>
> >Seems video distribution is not one of your areas of  expertise ?
>
> >  Note that John was talking about crosstalk, in the analog domain,
> >and yes, what he did certainly will have a measurable improvement, and
> >is somewhat 'industry practise' when minimising crosstalk.
> >  Note he says 'cured', that means he is on both sides of the problem,
> >and it is a brave (or something else?) person that counters such direct
> >experience
>
> >I imagine in extreme digital cases, such as where you are worried not
> >only about sending the clock, but also about the ps/fs of jitter, then
> >this design approach would also help : it's not hard to do.
>
> >-jg
>
> I do stuff down to a few ps RMS jitter on a regular 6 or 8-layer
> board, microstrip traces, with switching supplies and uPs and display
> drivers on the same board. Picoseconds aren't tough these days.
>
> John- Hide quoted text -
>
> - Show quoted text -

____________________________________

 You are hoping that we believe switchers
 cause lots of noise ....

   Zero ripple is what switchers do !
 The sudden pulse of current is only
 around a very short loop , it does
  not cause noise .
   They dont even have "ground loops"