PCB microstrip line capacitance

QuickField simulation example

This is an example of the microstrip line simulation, performed with QuickField software.

Engineering question
How to find microstrip transmission line capacitance

Engineering answer
Set up a plane-parallel QuickField Electrostatics problem for a PCB microstrip line and evaluate capacitance from computed field results.

Typical applications
PCB microstrip traces, microwave PCB traces, planar transmission lines

• Download simulation files (files may be viewed using any QuickField Edition).

Problem Type
Plane-parallel problem of electrostatics.

Geometry

Given
Relative permittivity of air ε = 1;
Relative permittivity of substrate ε = 10.
Shield is grounded U = 0 V.

Task
Determine the capacitance of the microstrip transmission line.

Solution
The capacitance is the ratio of stored electric charge to potential difference between the strip and the shield. We apply electric potential of 1V to the strip.

Result
Microstrip capacitance is 1.77e-10 [C] / 1 [V] = 0.177 [nF] per 1 meter of strip line length.

• Video: PCB microstrip line capacitance
  
• View simulation report in PDF.
• Download simulation files (files may be viewed using any QuickField Edition).