Tool Box

Microstrip Resistance

Microstrip Resistance

Microstrip Resistance Model
DC resistance of microstrip conductors is:
ACResistanceMicrostripFormula

where
DCResistanceTraceFormula
DCResistanceGroundFormula
Units: Ohms

AC resistance of microstrip conductors is:
ACResistanceMicrostripFormula
where
ACResistanceTraceFormulaLargeSkinDepth
ACResistanceTraceFormulaSmallSkinDepth

ACResistanceGroundFormulaLargeSkinDepth

ACResistanceGroundFormulaSmallSkinDepth
Units: Ohms

Skin Depth is:
SkinDepthFormula

Description
Resistance calculated using this tool includes both dc and ac resistance of microstrip conductors. At low frequencies, where skin depth is greater than conductor width and thickness is greater than ground plane thickness, ac resistance is approximately the same as the dc resistance. As frequency increases, ac resistance increases.

Assumptions and Limitations
Dimensions are in meters.
Trace conductor is assumed to have uniform circular cross section and to be uniformly spaced above the ground plane over its length.
Separation between the conductors is assumed to be large enough that proximity effect may be ignored.
Wire relative permeability: Symbol-muR
Wire relative conductivity: Symbol-sigmaR

Constants
Permeability of free space: Formula, Permeability of Free Space H/m
Conductivity of copper: Symbol-sigma0 = 5.98 x 10 7 S/m (Siemens per meter) at 20-degrees C

Reference: “Analysis of Multiconductor Transmission Lines,” 2nd Ed., Clayton R. Paul, 2008.

Inputs

Width
w
Trace Thickness
t
Ground Plane Thickness
g
Length
l
Frequency
f
Relative Conductivity
Relative Permeability

Outputs:

DC Resistance: R = 
8.779e-2 Ohms
AC Resistance: R = 
8.779e-2 Ohms
Skin Depth:  = 
2.058e-4 m