Notes:
 The formulas used here are taken from the Design
Guide for Electronic Packaging Utilizing HighSpeed
Techniques (4th Working Draft, IPC2251, February
2001).
 Range of valid parameters specified in the Design
Guide: W/(HT) < 0.35; T/H <0.25; 1 <
ε_{r} < 15
 Accuracy: For typical PCB parameters (ε_{r} = 4,
H = 15 mil, C = 10 mil and T = 1.37 mil), the deviation
of the calculated results from results obtained using
a 2D numerical field solver, is
listed below:
Z_{0}: 

W/(HT) < 0.04 
more than 30% 
0.04 < W/(HT) < 0.08 
within 5% 
0.08 < W/H < 0.35 
within 1% 
C_{0}: 

W/(HT) < 0.04 
more than 80% 
0.04 < W/(HT) < 0.08 
within 5% 
0.08 < W/H < 0.27 
within 10% 
0.27 < W/H < 0.35 
within 12% 
