Calculation method and supported range
Small-loss approximation. Homogeneous TEM: αd = πf√εr tanδ/c. Microstrip uses Hammerstad–Jensen εeff and filling factor εr(εeff−1)/[εeff(εr−1)]. Multiply Np/m by 20/ln(10) for dB/m.
Df: 0–0.05; Dk: 1–20. Microstrip uses t = 0 and the microstrip geometry bounds above (0.05 ≤ w/h ≤ 20). No conductor, roughness, radiation, mismatch or connector loss. This is not total insertion loss. Frequency dispersion and material temperature dependence are not modeled.
Technical sources
Using the result
A datasheet Df is tied to its test method and frequency. The output excludes conductor, roughness, radiation, connector and mismatch losses, so it must not be read as predicted total insertion loss. Match input Df to the intended operating conditions before comparing materials.
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.