Signal Decay
High-frequency signal amplitude reduction along printed circuit trace conductors results from dielectric absorption and conductor resistivity over distance. Quantifying transmission line attenuation determines maximum achievable trace lengths for multi-gigabit per second serial interconnects. Loss accumulates continuously as electromagnetic energy travels between transmitter outputs and receiver inputs.
Analysis applies to microstrip and stripline structures across multi-layer printed circuit board stackups.
Loss Breakdown
Total signal loss combines conductor resistance loss and dielectric dissipation loss. Conductor losses dominate at lower frequencies due to direct current trace resistance and skin effect current crowding near conductor surfaces. Dielectric losses increase linearly with frequency as resin molecules absorb electromagnetic energy within substrate dielectric layers.
Surface roughness at the copper-dielectric interface increases effective conductor path length, sharply boosting high-frequency attenuation rates. Smooth electrodeposited or rolled-annealed copper foils suppress skin effect losses in gigahertz interconnects.
Impedance Control
Fabricators minimize signal degradation by controlling copper foil treatment, dielectric layer thickness and trace cross-sectional dimensions. Vector network analyzers measure scattering parameters to evaluate signal power loss across operating frequency bands. Equalization techniques at circuit receivers compensate for high-frequency attenuation loss profiles.
Selecting smooth copper foils and low-loss resin systems preserves signal eye patterns over extended circuit board routing paths.
