NIST Iterative Method

Numerical Optimization

Standard analytical methods sometimes fail or diverge when processing scattering parameters of low-loss polymers. The nist iterative method avoids these instabilities by using a non-linear least-squares fitting algorithm that minimizes the difference between measured and calculated parameters. This optimization provides a highly reliable way to determine both the real and imaginary parts of permittivity.

Ambiguity Resolution

High-frequency wave propagation through thick substrates creates phase wraps that lead to multiple mathematical solutions. Because the nist iterative method uses a numerical search across a wide range of frequencies, it overcomes these phase wraps by finding the mathematically consistent value. This stability ensures that the extracted dielectric constant is accurate across a broad frequency band.

It avoids the failures that occur in non-iterative approaches when the sample thickness equals a multiple of a half-wavelength.

Material Characterization

Substrates for high-frequency communication boards must have highly stable and predictable permittivity values. Utilizing the nist iterative method in the material testing laboratory helps to verify that the raw substrates meet the strict requirements of automotive radar and fifty-g applications. This testing provides the high-fidelity dielectric data required for precise circuit simulation.