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Microstrip Transmission Line Characteristic Impedance Calculator

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


[diagram of PCB layers]

Relative Dielectric Constant ( εr ): 
Track Width:  mm
Track Thickness:   mm
Dielectric Thickness:   mm 
Effective Dielectric Constant (εeff): 
Characteristic Impedance (Zo):   Ohms

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

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

  More calculators for transmission line can be found at

[calculation equation]

[calculation equation]

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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