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Material Characterization by Millimeter-Wave Techniques

Andersson, Leonard LU (2016) EITM01 20151
Department of Electrical and Information Technology
Abstract
This master thesis investigates material characterization by reflection and transmission of electromagnetic waves in the 40-60 GHz band (millimeter-wave spectrum) for different materials. The free-space measurement method is a fast, efficient and non-destructive way of examining a material and is being researched by both academics and industries.
The theory of how electromagnetic waves interact with different materials such as dielectrics and conductors is reviewed as well as how the reflection and transmission from such materials can be computed theoretically. This theory is partially derived from Maxwell’s equations. From this theory, simulations are performed to get signal levels of reflection and transmission for different materials... (More)
This master thesis investigates material characterization by reflection and transmission of electromagnetic waves in the 40-60 GHz band (millimeter-wave spectrum) for different materials. The free-space measurement method is a fast, efficient and non-destructive way of examining a material and is being researched by both academics and industries.
The theory of how electromagnetic waves interact with different materials such as dielectrics and conductors is reviewed as well as how the reflection and transmission from such materials can be computed theoretically. This theory is partially derived from Maxwell’s equations. From this theory, simulations are performed to get signal levels of reflection and transmission for different materials and varying material parameters. From the simulations it is shown that certain materials are better examined in either transmission or reflection.
Measurements were performed in time domain (with a wavelet generator and an oscilloscope) and in frequency domain (with a network analyzer). Both reflection and transmission were measured for all samples. Four samples were investigated thoroughly: two PMMA (Poly(Methyl MethAcrylate)) samples, one silicon sample and a thin gold film sample.
Before the measured data can be compared to the simulated, it is necessary to apply signal processing to both the measured and the simulated data. This is done to make sure the comparison of the two data sets works and it consists of removing multiple reflections and other unwanted noise from the signal. The material characterization could then be performed, by extracting a specific material parameter, such as permittivity or conductivity. This is done by comparing simulated data iteratively to measured data. The best fit should then, in theory, correspond to the actual material parameter.
The material characterization worked, although sometimes differences in time and frequency domain were found. Permittivity values were extracted for the PMMA samples and conductivity values for the silicon and thin gold film samples. The values extracted compared well with reference values for the PMMA samples and the thin gold film sample. (Less)
Popular Abstract
Electromagnetic Material Characterization by Millimeter Wave Technologies

What if you could have a small gadget that you could put on any object or surface and it would give you its composition, its material parameters and more, in an instant?

Even though we are not quite there yet, we are undoubtedly moving in this direction. Needless to say, such a device would have tremendous areas of application. It could be used in industries as broad as chemistry, food science, civil engineering and much much more. Deciding a material’s characteristics, for example conductivity, permittivity or thickness, have up until recently been quite a troublesome ordeal. By using free space electromagnetic waves you get a fast, efficient and... (More)
Electromagnetic Material Characterization by Millimeter Wave Technologies

What if you could have a small gadget that you could put on any object or surface and it would give you its composition, its material parameters and more, in an instant?

Even though we are not quite there yet, we are undoubtedly moving in this direction. Needless to say, such a device would have tremendous areas of application. It could be used in industries as broad as chemistry, food science, civil engineering and much much more. Deciding a material’s characteristics, for example conductivity, permittivity or thickness, have up until recently been quite a troublesome ordeal. By using free space electromagnetic waves you get a fast, efficient and non-destructive way of probing a material. If all the material’s parameters are extrapolated, the material can be identified and classified.
This thesis presents a way of finding a material’s parameters with the help of electromagnetic waves, looking at the wave’s reflection and transmission from the material. The thesis investigates measurements in both time and frequency domain. The material characterization consists of comparing simulated to measured data and finding the best fit. Two dielectrics and two conductors were investigated thoroughly and either the permittivity or the conductivity values of these samples were extracted. (Less)
Please use this url to cite or link to this publication:
author
Andersson, Leonard LU
supervisor
organization
course
EITM01 20151
year
type
H2 - Master's Degree (Two Years)
subject
keywords
Material Characterization, time domain, frequency domain, reflection, transmission, free space, permittivity, conductivity, PMMA, Silicon, Measurement
report number
LU/LTH-EIT 2016-488
language
English
id
8851879
date added to LUP
2016-03-29 14:34:19
date last changed
2016-05-11 14:31:30
@misc{8851879,
  abstract     = {This master thesis investigates material characterization by reflection and transmission of electromagnetic waves in the 40-60 GHz band (millimeter-wave spectrum) for different materials. The free-space measurement method is a fast, efficient and non-destructive way of examining a material and is being researched by both academics and industries. 
The theory of how electromagnetic waves interact with different materials such as dielectrics and conductors is reviewed as well as how the reflection and transmission from such materials can be computed theoretically. This theory is partially derived from Maxwell’s equations. From this theory, simulations are performed to get signal levels of reflection and transmission for different materials and varying material parameters. From the simulations it is shown that certain materials are better examined in either transmission or reflection.
Measurements were performed in time domain (with a wavelet generator and an oscilloscope) and in frequency domain (with a network analyzer). Both reflection and transmission were measured for all samples. Four samples were investigated thoroughly: two PMMA (Poly(Methyl MethAcrylate)) samples, one silicon sample and a thin gold film sample. 
Before the measured data can be compared to the simulated, it is necessary to apply signal processing to both the measured and the simulated data. This is done to make sure the comparison of the two data sets works and it consists of removing multiple reflections and other unwanted noise from the signal. The material characterization could then be performed, by extracting a specific material parameter, such as permittivity or conductivity. This is done by comparing simulated data iteratively to measured data. The best fit should then, in theory, correspond to the actual material parameter. 
The material characterization worked, although sometimes differences in time and frequency domain were found. Permittivity values were extracted for the PMMA samples and conductivity values for the silicon and thin gold film samples. The values extracted compared well with reference values for the PMMA samples and the thin gold film sample.},
  author       = {Andersson, Leonard},
  keyword      = {Material Characterization,time domain,frequency domain,reflection,transmission,free space,permittivity,conductivity,PMMA,Silicon,Measurement},
  language     = {eng},
  note         = {Student Paper},
  title        = {Material Characterization by Millimeter-Wave Techniques},
  year         = {2016},
}