Ohmic Loss
Understanding Ohmic Loss
Ohmic loss results from current flowing through conductors with non-zero resistance. At RF frequencies, the skin effect confines current to a thin surface layer (skin depth), increasing the effective resistance. Skin depth decreases as 1/sqrt(f).
Gold, silver, and copper plating minimize ohmic loss. In waveguides, ohmic loss increases with frequency and decreases with waveguide size. Surface roughness significantly increases ohmic loss at millimeter-wave frequencies by extending the current path.
Frequently Asked Questions
How does skin effect increase ohmic loss?
Skin effect confines RF current to a thin surface layer, reducing the effective cross-section and increasing resistance. At 10 GHz, the skin depth in copper is only about 0.66 micrometers.
How is ohmic loss minimized?
Using high-conductivity metals (silver, copper, gold plating), smooth surface finishes, and larger waveguide cross-sections reduces ohmic loss.