Microstrip Line Impedance Calculator

This page provides information and calculators related to microstrip line impedance.

EXAMPLE:

• Relative permittivity = 10.9
• h = 0.635 mm
• W = 0.5mm

Result: Impedance = 52.31 Ohm, Effective permittivity = 7.18 (1 mm = 39.37 mils)

Microstrip Line Impedance Equation

A microstrip line is an inhomogeneous transmission line structure. It’s fundamentally composed of three layers:

• Top Layer: A strip conductor etched according to the circuit layout.
• Middle Layer: A dielectric material.
• Bottom Layer: A completely metallized ground plane.

This microstrip line configuration is widely used due to its ease of fabrication using photolithographic processes. After etching, active and passive components can be easily soldered, providing straightforward access to the top layer. This also makes troubleshooting RF modules designed with microstrip lines much simpler.

The following equations are used to calculate the effective permittivity and impedance of a microstrip line:

Microstrip line effective permittivity equation:

Microstrip line impedance equation: