Enter the relative permitivity, width of the trace, the ground plane spacing, and the substrate thickness to calculate the characteristic impedance.

Tee Attenuator

Note: Units do not matter for this calculation as long as they are consistent.

Reference: R. Simons, "Coplanar Waveguide Circuits, Components, and Systems", Wiley, 2001, pp. 15-21.

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Additional notes: this calculation assumes that there is no ground-plane underneath the dielectric, and below it is free space or air.

Try this calculator on sourceforge for grounded CPW:


Many equations have been applied to CPW impedance calculations to model its behavior. The equations we used are not the most accurate and the results should be considered approximate, for example, the calculation does not take into account the thickness of the strips. For critical designs you should consider using 3D electro-magnetic analysis of CPW.

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