Microstrip & Stripline Impedance Calculator
This calculator estimates the characteristic impedance (Z₀) and propagation delay for Microstrip and Stripline transmission lines based on standard IPC-2141 formulas.
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Microstrip & Stripline Fundamentals
Microstrip Line:
A transmission line trace routed on the external layer of the PCB over a reference ground plane. Since the EM wave propagates partly in air and partly in the dielectric substrate, its effective dielectric constant is lower than the substrate itself. Calculated via IPC-2141:
$$Z_0 = \frac{87}{\sqrt{\epsilon_r + 1.41}} \ln\left( \frac{5.98 H}{0.8 W + T} \right)$$
Stripline:
An internal signal trace sandwiched between two ground planes. Because the dielectric medium is homogeneous, it offers superior EMI protection and is highly suited for high-speed differential signal designs:
$$Z_0 = \frac{60}{\sqrt{\epsilon_r}} \ln\left( \frac{1.9 B}{0.8 W + T} \right)$$