Calculation method and supported range
Hammerstad–Jensen (1980), including normalized finite-thickness width and effective-permittivity corrections. Width synthesis uses bounded bisection of the same model.
Quasi-static, single trace above an infinite ground, air above, uniform isotropic nonmagnetic substrate. Supported tool range: 1 ≤ Dk ≤ 20, 0.05 ≤ w/h ≤ 20, t/h ≤ 0.2 and t/w ≤ 0.25. No solder mask, dispersion, loss, roughness or nearby copper is included. Validate the finished stackup with a field solver and measurement.
Technical sources
Using the result
Measure dielectric height from the lower surface of the trace to its reference plane. Specify copper thickness separately. Solder mask, roughness, finite ground, pads and connectors require a more complete model. Use the synthesized width as the starting point for a fabricator-approved stackup.
From a calculation to a released design
Keep the input assumptions with the result. Recalculate when the ordered material, dielectric height, copper or operating conditions change. Confirm the final construction with the fabricator and use field simulation or measurement wherever the simplified model omits an important effect.
See the controlled-impedance guide and material selection workflow for the next checks.