Free Space Dielectric Property Extraction for Automotive Radar Polymer Enclosures
Precision W-band free-space extraction of polymer permittivity prevents radar boresight shift and avoids costly Class II Permissive Change re-testing delays.
Nicholson-Ross-Weir Algorithm
Meaning
Mathematical method calculates the complex permittivity and permeability of a material from its measured reflection and transmission coefficients. The nicholson-ross-weir algorithm is widely used in radio frequency laboratories to analyze the electromagnetic properties of substrate samples. This calculation relies on the relationship between scattering parameters and the wave impedance of the medium.
Parameter Conversion
High-frequency network analyzers measure how much signal is reflected and transmitted by a test sample. The nicholson-ross-weir algorithm takes these scattering parameters and converts them directly into dielectric and magnetic properties. This conversion provides a rapid way to characterize new materials across a broad frequency band.
Mathematical Ambiguity
Phase wraps occur when high-frequency signals pass through thick samples, which creates multiple possible mathematical solutions. When using the nicholson-ross-weir algorithm, these multiple solutions occur at integer multiples of the wavelength inside the material. This ambiguity requires the engineer to choose the correct solution based on the physical thickness or a known reference value.
It can be resolved by combining the measurement with a low-frequency estimate or utilizing thinner samples.
Waveguide Extraction
Placing a sample inside a closed waveguide provides a stable, controlled environment for the measurement. The algorithm processes the s-parameters collected from the waveguide ports to extract the material parameters. This technique is highly effective for low-loss polymers used in the manufacturing of high-frequency communication devices.