Coplanar Waveguide With Ground Characteristic Impedance Calculator

The characteristic impedance (Z_o) of coplanar waveguide with ground or microstrip lines with signal side ground plane can be calculated using the active calculator or the equations at the bottom of the page.

[Diagram of PCB layers]

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The original equations are in Transmission Line Design Handbook by Brian C Wadell, Artech House 1991 page 79. The equations use "a" for the track width and "b" for the sum of the track width plus the gaps either side.

[Coplanar waveguide equations]

To avoid microstrip line modes, it is recommended that h >> b and that the component side ground extend away from the track on each side more than "b".

Note: For those who wish to understand how K(k) is found, there is a calculator and equations for Elliptical Integrals of the First Kind

This calculator is provided free by Chemandy Electronics in order to promote the FLEXI-BOX

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	INPUT DATA

Relative Dielectric Constant ( ε_r):
Track Width (S):	mm
Gap Width (W):	mm
Dielectric Thickness (h):	mm

	RESULTS

Effective Dielectric Constant (ε_eff):
Characteristic Impedance (Zo):	Ohms