Nicolson-Ross-Weir Research Articles

Electromagnetic Characterization of Layered Materials via Direct and De-embed Methods

Electromagnetic-material characterization is the process of determining the permittivity and permeability of matter. One of the predominant schemes utilized for computing these constitutive parameters is the Nicolson-Ross-Weir (NRW) algorithm. In this particular technique, the sample under measurement is assumed to be linear, homogeneous, isotropic (i.e., simple medium), and is comprised of a single-layer planar material. However, samples are frequently attached to known substrate materials in order to facilitate measurement; thus, the standard NRW technique cannot be directly employed. This paper presents two schemes, the direct and de-embed methods, for accommodating multilayered-material-characterization measurements. Accuracy is discussed using an uncertainty analysis. In addition, it is shown that the direct method has a distinct advantage over the de-embed method if sample homogeneity is to be monitored.

Determination of microwave intrinsic properties of hexaferrite samples

Measurements of dielectric and magnetic properties of hexaferrite samples within the 8–16 GHz band using a rectangular waveguide are presented. The data are retrieved using the Nicolson–Ross–Weir (NRW) T/R method. Graphs of relative uncertainty for the permittivities' and permeabilities' measured and expected reflection losses for a metal-backed single-layer absorber are shown. © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 16: 393–397, 1997.

Determination of microwave intrinsic properties of hexaferrite samples

Measurements of dielectric and magnetic properties of hexaferrite samples within the 8–16 GHz band using a rectangular waveguide are presented. The data are retrieved using the Nicolson–Ross–Weir (NRW) T/R method. Graphs of relative uncertainty for the permittivities' and permeabilities' measured and expected reflection losses for a metal-backed single-layer absorber are shown. © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 16: 393–397, 1997.

Noniterative stable transmission/reflection method for low-loss material complex permittivity determination

This paper describes a new noniterative transmission/reflection method applicable to permittivity measurements using arbitrary sample lengths in wide-band frequencies. This method is based on a simplified version of the well-known Nicolson-Ross-Weir (NRW) method. For low-loss materials, this method is stable over the whole frequency range: no divergence is observed at frequencies corresponding to integer multiples of one half wavelength in the sample. The accuracy on the dielectric permittivity is similar to that obtained with a more recently proposed iterative technique. A general equation for complex permittivity determination including the Stuchly, NRW, and new noniterative methods, is also proposed.

New ultrasonic machine tool: Metallurgia, 76, No. 456, pp 157–158 (October 1967)

An improved Nicolson–Ross–Weir (NRW) algorithm is obtained by incorporating an impedance-mismatch factor and reference-plane-correction factors into the equations. Impedance mismatch and reference plane position are sources of error in the extraction of the permittivity and permeability of low-loss fluids. To apply the algorithm, a detailed model of the coaxial cell is developed for the calculation of the full scattering equations. The new model fits experimental data and reduces to the model commonly found in the literature for such cells. Measurements and simulations were carried out in the 300 kHz to 3 GHz frequency range.