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Effect of Conductor Surface Roughness in Electromagnetic Analysis

The conductor surface roughness affects the simulation in electromagnetic analysis. If the surface roughness is as deep as the skin depth,

the conductor's resistance is higher than that of smooth-surface conductor. The conductivity is adjusted along with the rate the resistance increases.

The equation (3) shown below is for the conductivity σc of conductor with rough surface.

 

 

αc,0: conductor loss with smooth surface

αc: conductor loss with rough surface

f: frequency

δ: skin depth

Δ: RMS surface roughness

μ: permeability

σ: Conductivity

σc: conductivity with surface roughness taken into account

 

Fig.1 show the loss calculated by equation (2). The horizontal axis is the surface roughness normalized by the skin depth.

 

Surface roughness / Skin depth δ

Figure 1. α: Conductor loss with rough surface α0: Conductor loss with smooth surface

 

 

 

The equations (1) and (2) are shown in the reference [1].

 

Reference[1]: Transmission Line Design Handbook Brian C.Wadell Artech House

3.5.1.2.2 Effect of Conductor Surface Roughness