Three dielectric values answer different questionsRT/duroid 5880 vs RO4003C. Engineering illustration, not a production photograph or test result.Three dielectric values answer different questionsRT/duroid 5880 vs RO4003CProcess DkSupplier test methodMaterial controlDesign DkConstruction / methodCircuit model inputEffective DkLine + surroundingsPropagation resultKeep frequency, temperature, method and construction with each value.A test tolerance is not automatically a finished-circuit impedance tolerance.