Dissertation
Dissertation > Industrial Technology > Electrotechnical > Electrical measurement techniques and instruments > Magnetic quantity measurements and instrumentation

Calculate the Permittivity and Permeability from Scatter Parameter through Group Delay Method by Python Program

Author ShiJianRong
Tutor Yang
School Nanjing University
Course IC
Keywords Vector network analyzer (VNA) group delay (GD) python
CLC TM936
Type Master's thesis
Year 2013
Downloads 22
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The measurement in the microwave frequency range of complex electromagnetic properties of the material has attracted more and more attention, especially in many of our well-known areas of research, such as materials science, microwave circuit design, the development of the absorber, and biological research. The microwave measurement is important for it can provide electrical and magnetic properties of materials, which have been proved to be useful for many research fields. Many methods have been developed to measure the properties of these complicated properties, such as time domain and frequency domain method, single-port and dual-port measurement methods. But all the methods are limited by the specific frequency or application field. As the development of new technologies, the vector network analyzer emerges and can be used to measure the reflection and transmission coefficients, and then the parameters can be converted to the microwave parameters of materials by the appropriate software. The purpose of this thesis is to describe the general procedure used to calculate electromagnetic properties of materials from the measured S-parameters. However, due to the existence of multi-valued issue while calculating complex electromagnetic parameters from scattering parameters, a variety of solutions have been proposed to solve the problem of multi-value and half-wavelength data divergence by many experts in the world, such as redundant comparison method, the imaginary part compensation law, and using short sample to solve the problem of the half-wavelength data result divergence, or rewriting the equations to make the denominators not approach0, theoretically eliminating the half-wave resonance problems. The computer language Python is designed to be extensible and not all features and functions are integrated into the kernel of the language. Python provides a rich set of APIs and tools, so that programmers can easily use the C language, C++, Cython to write an expansion module. Python compiler itself can also be integrated into other scripting language program. Therefore, many people also use Python as a "glue language"(glue language), with the ability of integrating and packaging programs written in other languages, python program is a completely open source software, in addition to its own math package and cmath package, while the majority of developers to write the scientific computing program, as described in this thesis use the NumPy as well as Matplot drawing software. In this thesis, the use of measured data from the vector network analyzer, the preparation of the corresponding python program to pre-read the vector network analyzer measured data and preliminary data processing module read through the file, and then passed to the data computing module using the group delay of the method to calculate the complex electromagnetic parameters of the method, by calculating the group delay values and the measured group delay to determine the value of n, so as to solve the multi-value problems of the n values, and at the same time to solve the half-wavelength multiples Data divergence. And then use the drawing module team data results drawing, making a more intuitive data comparison and understanding. Finally, the error analysis of the data, error analysis, data calculated in the case of possible errors, the way boasts tolerance for error.

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