CHEMANDY ELECTRONICS Suppliers of the unusual

Microstrip Transmission Line Characteristic Impedance Calculator

The characteristic impedance (Zo) of a microstrip transmission line can be calculated using the active calculator or the formulas at the bottom of the page.

[diagram of PCB layers]


Enter the εr of the PCB: 
Enter the width of the track:   mm
Enter the thickness of the track:    mm Effective Dielectric Constant (εeff): 
Enter the thickness of the dielectric:     mm  Characteristic Impedance (Zo):   Ohms

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The following formulas are from an article by Rick Hartley page 27

The formulas give results within 3% of the results obtained in 

More calculators for transmission line can be found at

[calculation formula]

[calculation formula]

Where εr is the Relative Dielectric Constant

W is the Width of track

t is the Thickness of track (1 oz/ft2 = 0.035 mm)

h is the Thickness of dielectric

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

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