Coplanar Waveguide Calculator

Use the units printed beside each field. On a small screen, scroll the calculator horizontally to see all inputs and results.

		er
		s		[mm]
		h		[mm]
		t		[um]
		fo		[MHz]

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w		[mm]		>>> Zo		[ohm]
Zo		[ohm]		>>> w		[mm]

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er eff

k

lambda/4

[mm]

Inputs and units

er

Relative permittivity of the substrate.

s (mm)

Centre conductor width in this calculator’s diagram.

w (mm)

Gap between the centre conductor and adjacent ground conductor.

h (mm)

Substrate thickness.

t (µm)

Conductor thickness in micrometres.

fo (MHz)

Operating frequency.

Zo (Ω)

Target impedance for gap synthesis.

How to use this calculator

Enter substrate properties, centre conductor width s and gap w, then choose Analyze. To estimate a gap for your required impedance, enter Zo and choose Synthesis. Do not interchange the centre width and the gap.

Reading the results

Read impedance in ohms and synthesized dimensions in millimetres. Effective permittivity and velocity factor describe the propagation estimate; the quarter-wavelength output is in millimetres.

Before using the result in a design

This page and the grounded CPW calculator represent different geometries. If your board has a backing ground plane, use the grounded CPW tool. Finite ground width, vias, solder mask and fabrication tolerances require further design verification.

Blank fields use the tool’s built-in example defaults; always enter and check your actual design values.

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