It is possible to calculate the permittivity/permeability based on the S parameter of the transmission line including the material to be measured.
The method is ideal for evaluating the frequency response of the material. On the other hand, the measurement accuracy is limited by the network analyzer accuracy,
and it is often not suitable for low-loss material evaluation. (Resonator perturbation method is effective for evaluating low loss materials. )
Combined with the Keysight material measurement suite N1500A, efficient and reliable material measurement can be performed. The N1500A
supports a variety of algorithms, among which representative ones are listed below.
| N1500A | model | Parameters used | Material Parameters | Summary |
|---|---|---|---|---|
| Reflection/ Transmission Mu and Epsilon | Nicholson- Ross-Weir (NRW) |
S11, S21, S12, S22 |
εr μr | Developed by Nicholson and Ross, later applied by Weir to the network analyzer. Discontinuities may occur in low loss samples with thicknesses above half a wavelength. Ideal for evaluating magnetic materials such as ferrite and radio wave absorbers. |
| Reflection/ Transmission Epsilon Precision | NIST Precision |
S11, S21, S22 | εr | Developed by NIST to calculate the permittivity from the S parameter. Ideal for relatively thick low loss dielectric material samples. |
| Transmission Epsilon Fast | Fast Transmission |
S21, S12 | εr | Predict the permittivity, then minimize the difference between the predicted S parameters and the measured values into the predefined limits. It is suitable for thick low loss dielectric material especially if reflection measurement includes significant errors. |