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