Scattering parameter extraction and optimization
scatter_opt is a MatLab package for processing electromagnetic scattering parameter data.
Disclaimer
This is a package that I hastily developed to help a friend with a research project. I have not touched it since 2020. It has been tested reasonably thoroughly, but I cannot guarantee the results or provide full support! I am making it available in case it helps someone process their data and/or get started on their own code.
Documentation
The "scatter-opt documentation" Word document walks through a fitting example and provides class and function documentation. In addition, the file fitting_examples_0408.m provides the code for the full fitting process with several different options shown. Unfortunately, I am not in a position to provide support for this package, but hopefully these examples will help you get started.
Features
scatter_opt currently implements the following techniques:
- Nicholson-Ross-Weir (NRW) [1,2] and new non-iterative (NNI) [3] methods for permittivity and permeability extraction from S parameters
- Group delay method for branch selection as described by Weir [2]
- Kramers-Kronig method for branch selection as described by Szabó et al. [4]
- A new method for branch selection that is valid at high frequencies (unlike group delay) and does not suffer from truncation error (unlike the conventional Kramers-Kronig method)
- Nonlinear least-squares optimization of permittivity and permeability as described by Domich, Baker-Jarvis, and Geyer [5,6]
 
 
 
 
References
- Nicolson, A. M., & Ross, G. F. (1970). Measurement of the Intrinsic Properties Of Materials by Time-Domain Techniques. IEEE Transactions on Instrumentation and Measurement, 19(4), 377–382. https://doi.org/10.1109/TIM.1970.4313932
- Weir, W. B. (1974). Automatic Measurement of Complex Dielectric Constant and Permeability at Microwave Frequencies. Proceedings of the IEEE, 62(1), 33–36. https://doi.org/10.1109/PROC.1974.9382
- Boughriet, A. H., Legrand, C., & Chapoton, A. (1997). Noniterative stable transmission/reflection method for low-loss material complex permittivity determination. IEEE Transactions on Microwave Theory and Techniques, 45(1), 52–57. https://doi.org/10.1109/22.552032
- Szabó, Z., Park, G. H., Hedge, R., & Li, E. P. (2010). A unique extraction of metamaterial parameters based on Kramers-Kronig relationship. IEEE Transactions on Microwave Theory and Techniques, 58(10), 2646–2653. https://doi.org/10.1109/TMTT.2010.2065310
- Domich, P. D., Baker-Jarvis, J., & Geyer, R. G. (1991). Optimization techniques for permittivity and permeability determination. Journal of Research of the National Institute of Standards and Technology, 96(5), 565–575. https://doi.org/10.6028/jres.096.033
- Baker-Jarvis, J., Geyer, R. G., & Domich, P. D. (1992). A Nonlinear Least-Squares Solution with Causality Constraints Applied to Transmission Line Permittivity and Permeability Determination. IEEE Transactions on Instrumentation and Measurement, 41(5), 646–652. https://doi.org/10.1109/19.177336