microstrip line width

calculate the width of the trace for micro-strip lines according to the characteristic impedance.


Parameters

characteristic impedance
`Z_0` \(\Omega\)
dielectric constant
`epsilon_r` \(\)
height of the substrate
h \(mil\)

Output

factor  A

ratio A 

`w/h=(8e^A)/(e^(2A)-2)`

factor  B

`60pi^2/(Z_0 sqrt(epsilon_r))`

ratio B 

`W/h=2/pi{B-1-ln(2B-1)+(epsilon_r-1)/(2epsilon_r)[ln(B-1)+0.39-0.61/epsilon_r]}`

width w

`ra(ra<=2)+rb(rb>2)`

w in mm 

`1mil=0.0254mm'