Question: Does anybody know how to calculate the width of a 50 Ohm
microstrip line on Arlon PTFE circuit board (Type GX-0065-45-11). It is
0.0065" thick, double sided and has a k=2.45. Looking at my chart, it
looks like I leave the bottom as complete copper groundplane and take
off all copper around stripline on the top side of the board and leave
the stripline as 0.0195" wide? That doesn't sound very wide!!

Scott
N0EDV

Scott wrote:

Question: Does anybody know how to calculate the width of a 50 Ohm
microstrip line on Arlon PTFE circuit board (Type GX-0065-45-11). It is
0.0065" thick, double sided and has a k=2.45. Looking at my chart, it
looks like I leave the bottom as complete copper groundplane and take
off all copper around stripline on the top side of the board and leave
the stripline as 0.0195" wide? That doesn't sound very wide!!

Scott
N0EDV

..0065 is paper thin, possibly less.

1/16 inch is 0.063 -- did you slip a digit?

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Posting from Google? See http://cfaj.freeshell.org/google/

"Applied Control Theory for Embedded Systems" came out in April.
See details at http://www.wescottdesign.com/actfes/actfes.html

Scott wrote:

Question: Does anybody know how to calculate the width of a 50 Ohm
microstrip line on Arlon PTFE circuit board (Type GX-0065-45-11). It is
0.0065" thick, double sided and has a k=2.45. Looking at my chart, it
looks like I leave the bottom as complete copper groundplane and take
off all copper around stripline on the top side of the board and leave
the stripline as 0.0195" wide? That doesn't sound very wide!!

Scott
N0EDV

It isn't very wide at all.

I've built stuff on 15 mil 5880, twice as thick as your
paper-thin material. And it was still a handful.

What are you building? Why so thin?

Laura Halliday VE7LDH "That's a totally illegal,
Grid: CN89mg madcap scheme. I like it!"
ICBM: 49 16.05 N 122 56.92 W - H. Pearce

Nope...the stuff I have IS paper thin. Very flexible. Bought it to use
on upper UHF and into the microwaves. I didn't measure it with a
micrometer, but I will do that later and report back...

Scott



Tim Wescott wrote:

Scott wrote:

Question: Does anybody know how to calculate the width of a 50 Ohm
microstrip line on Arlon PTFE circuit board (Type GX-0065-45-11). It
is 0.0065" thick, double sided and has a k=2.45. Looking at my chart,
it looks like I leave the bottom as complete copper groundplane and
take off all copper around stripline on the top side of the board and
leave the stripline as 0.0195" wide? That doesn't sound very wide!!

Scott
N0EDV


.0065 is paper thin, possibly less.

1/16 inch is 0.063 -- did you slip a digit?

Scott wrote:
Question: Does anybody know how to calculate the width of a 50 Ohm
microstrip line

Scott:

There are lots of computer programs around that will do the calculation
for you. MWI.EXE is one....see
http://www.rogerscorporation.com/mwu...va/mwiform.htm for download.
You may also find the WA1MBA email list useful for questions like this
(see www.wa1mba.org )

73,
Steve VE3SMA

The reason I bought it was that there was a whole bunch of it available
at the Central States VHF Society conference this past weekend. They
did have some slightly thicker stuff and maybe I should've bought some
of that as well. Oh well, I'm stuck with this, so I'll have to try to
use it...it's for a homebrew 902 beacon using a few MAR-4 devices. I
will have to measure the lead width on these devices, but they might
just be about the same as my calculated stripline width of 0.0195".
This would be a good thing, but I agree, it may be a bit challenging to
make a strip that narrow on the board (a magnifying lens and a very
sharp scalpel!)....

Scott


laura halliday wrote:

Scott wrote:


Question: Does anybody know how to calculate the width of a 50 Ohm
microstrip line on Arlon PTFE circuit board (Type GX-0065-45-11). It is
0.0065" thick, double sided and has a k=2.45. Looking at my chart, it
looks like I leave the bottom as complete copper groundplane and take
off all copper around stripline on the top side of the board and leave
the stripline as 0.0195" wide? That doesn't sound very wide!!

Scott
N0EDV


It isn't very wide at all.

I've built stuff on 15 mil 5880, twice as thick as your
paper-thin material. And it was still a handful.

What are you building? Why so thin?

Laura Halliday VE7LDH "That's a totally illegal,
Grid: CN89mg madcap scheme. I like it!"
ICBM: 49 16.05 N 122 56.92 W - H. Pearce

Thanks for the tip! I'll check them out...

Scott



wrote:

Scott wrote:

Question: Does anybody know how to calculate the width of a 50 Ohm
microstrip line


Scott:

There are lots of computer programs around that will do the calculation
for you. MWI.EXE is one....see
http://www.rogerscorporation.com/mwu...va/mwiform.htm for download.
You may also find the WA1MBA email list useful for questions like this
(see www.wa1mba.org )

73,
Steve VE3SMA

Scott wrote:
The reason I bought it was that there was a whole bunch of it available
at the Central States VHF Society conference this past weekend. They
did have some slightly thicker stuff and maybe I should've bought some
of that as well. Oh well, I'm stuck with this, so I'll have to try to
use it...it's for a homebrew 902 beacon using a few MAR-4 devices. I
will have to measure the lead width on these devices, but they might
just be about the same as my calculated stripline width of 0.0195".
This would be a good thing, but I agree, it may be a bit challenging to
make a strip that narrow on the board (a magnifying lens and a very
sharp scalpel!)....

I know you already have the material, but for such a
low frequency and non-critical application I'd use plain
old 1/16" G-10 pc board. YMMV.

Mini-Circuits have an excellent on-line catalogue
(http://www.minicircuits.com), and the lead width
of a MAR-4 is indeed .02 inches. This seems small,
but I'm at work and all my MMICs are at home... :-)

Laura Halliday VE7LDH "That's a totally illegal,
Grid: CN89mg madcap scheme. I like it!"
ICBM: 49 16.05 N 122 56.92 W - H. Pearce

If the dielectric material is 6.5 mils thick and the copper is very
thin, the width needs to be 18.7 mils. If the substrate material is
0.0065 inches thick and the copper is "one ounce" (1.4 mils thick), the
width needs to be 17.3 mils. If the total thickness is 6.5 mils, and
that thickness includes top and bottom layers of "one ounce" copper
(leaving 3.7 mils of dielectric), the thickness needs to be 9.5 mils.

Good luck!

Roy Lewallen, W7EL

Scott wrote:
Question: Does anybody know how to calculate the width of a 50 Ohm
microstrip line on Arlon PTFE circuit board (Type GX-0065-45-11). It is
0.0065" thick, double sided and has a k=2.45. Looking at my chart, it
looks like I leave the bottom as complete copper groundplane and take
off all copper around stripline on the top side of the board and leave
the stripline as 0.0195" wide? That doesn't sound very wide!!

Scott
N0EDV

Correction:

The last sentence should end ". . . the width needs to be 9.5 mils."

Roy Lewallen, W7EL

Roy Lewallen wrote:
If the dielectric material is 6.5 mils thick and the copper is very
thin, the width needs to be 18.7 mils. If the substrate material is
0.0065 inches thick and the copper is "one ounce" (1.4 mils thick), the
width needs to be 17.3 mils. If the total thickness is 6.5 mils, and
that thickness includes top and bottom layers of "one ounce" copper
(leaving 3.7 mils of dielectric), the thickness needs to be 9.5 mils.