Difference between revisions of "Projects:2018s1-175 Split-ring resonators for measuring spatially-distributed complex permittivity at microwave frequencies"

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== Introduction ==
 
== Introduction ==
  
−
Split Ring Resonator (SRR) is an electromagnetic metamaterial which can be used as a sensing device. This project are developed to produce a 2D permittivity mapping for different types of material under test (MUT). A device which using SRR as a sensing device were produced with a varactor to load the DC voltage replacing VNA and 3 dimension testing of scanning system.
+
Split Ring Resonator (SRR) is an electromagnetic metamaterial which can be used as a sensing device. This project is developed to produce a 2D permittivity mapping for different types of material under test (MUT). A device that used SRR as a sensing device is produced with a varactor to load the DC voltage to replace the Voltage Network Analyser (VNA) and 3 dimension testing of scanning system.
 +
                                            [[File: Gambarsystem.png|System Overview|thumb|1000px|]]
  
−
== Project Aims and Motivation ==
+
The figure shows how the system that is built from last project. This year, the project changed the system so that it will be more effective. The varactor is included to the SRR to replace the VNA and a new system that can provide 3D scanning is added to replace the 2D system made by last year project.
  
−
The aims of this project is to make the SRR sensing device produced by the last year group to be functioned as ideally as possible. This aims can make the SRR sensing device being used in industry to studies of fossil or using as raw material quality analysis.
+
==Project Group Members==
−
The motivation to do this project is based on the quality produce from the last year project. By reading the report from last year project, we can see that the quality can be improved to make the product lucrative devices to be used in industry. We can see that the resolution can be increase to get better quality result and choosing the laser based sensor which more robust and resilient to reflection and attenuation factor . Other than that, removing the bulky VNA were made to get better portable network analyser.
 
  
 +
1. Izatul Natasha Zulkefli
  
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== BackGround ==
+
2. Liang Cheng
  
−
SRR is artificially produced structure common to metamaterials which can produce the desired magnetic susceptibility and also alter the electromagnetic properties of materials.
+
3. Ziyuan Wang
  
 +
==Project Supervisors==
  
−
== Method ==
+
1.  Dr. Withawat Withayachumnankul
  
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'''Increase Resolution of SRR'''
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2. Professor Christophe Fumeaux
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The objective of this method is to develop sensing device which has better resolution by fabricate the SRR more precisely. This can be achieved by using the Ansys HFSS software by designing the SRR in the simulation and after successfully getting result, the SRR will be fabricated. At the end, this SRR can be tested with Interface of LabVIEW, VNA and Microcontroller.
+
 
−
There are a few requirement and challenge to do this method. Some requirement to design SRR is  
+
== Project Aims and Approached ==
−
1. Responsive to frequency shift
+
 
−
2.Quality factor increase with practical limits
+
The aim of this project is to make the SRR sensing device produced by the last year group to have higher sensitivity in scanning the MUT.
−
3.Design must exploit the fringing effect
+
There are three approached that been explore to increase the sensitivity of the sensing device using SRR.
−
4.Design must be manufacturable
+
 
−
And the challenge to this design is
+
'''1. Designing different design of SRR'''
−
1. Scanning height and resolution as the height and resolution is inversely proportional relation.
+
 
−
2.Challenge to maintain the size of SRR and the resonant frequency.
+
Designing the SRR is the main part of the project for increasing of the sensitivity. This designing process had considered many types of factor so that the SRR can works well when tested with different types of MUT. The shape of SRR had been maintained from the previous shape which is in triangle shape as this shape can give better resolution . As for the design, the microstrip had been change to match with the 50 ohm characteristic impedance for impedance matching with the port. The SRR also were designed with almost no thickness so that it can give better resolution besides can made the varactor being soldiered easily on the SRR. Two inductance line were made to supply dc voltage and stopping the RF signal.
−
3. VNA limit the resonant frequency to 3GHz
+
 
 +
'''2. Load Varactor on the SRR'''
 +
 
 +
Varactor is a diode that can vary its capacitance by loading the DC voltage. This special characteristic made varactor suitable to replaced the VNA . VNA were used by the previous group to produced the change of the resonance shift when MUT are placed under the SRR. This function were replaced by varactor which vary the DC voltage to get the reading of the frequency shift.
 +
 
 +
'''3. 3 Dimension Sensing'''
 +
 
 +
The permittivity mapping are done by 2 dimension mapping by last year project. As to increase the permittivity mapping function, a system which allow 3 dimension mapping (x,y and z axis) were produced.
 +
 
 +
== Project Design==
 +
 
 +
[[File: Screen_Shot_2018-10-18_at_1.55.36_PM.png]]
 +
 
 +
 
 +
The cycle shows how the overview of the project structure. Starting with SRR as a sensing device to test with different MUT. Then, the system continue with the power detector getting the measurement of the power signal produced by the SRR. This power signal then being analysed by the arduino board which had coded to pass the reading of the power signal to the Digital Analog Converter. This reading were then received by the varactor to produce the result of frequency shift made by the SRR.
 +
 
 +
 
 +
== Design and Hardware ==
 +
 
 +
'''SRR'''
 +
 
 +
 
 +
SRR were design as shown in figure below :
 +
 
 +
[[File: Screen_Shot_2018-10-18_at_1.59.48_PM.png ]]
 +
 
 +
Substrate              : Substrate that had been used is fr4 which has relative permittivity of 4.3.
 +
 
 +
Microstrip line      : Microstrip line with width of 3.162mm with almost no thickness were used to get the impedance characteristic of 50 ohm for impedance matching.
 +
 
 +
Varactor                : loaded on the SRR used for changing the resonance frequency.
 +
 
 +
Conductance line : Used for RF choke which supply DC voltage and stop the flowing of RF Signal.
 +
 
 +
 
 +
'''Power Detector'''
 +
 
 +
 
 +
[[File: Screen_Shot_2018-10-18_at_2.18.33_PM.png ]]
 +
 
 +
This power detector are used to measure the voltage amplitude produced by SRR.
 +
 
 +
 
 +
'''DAC And Arduino'''
 +
 
 +
 
 +
[[File:Screen Shot 2018-10-18 at 2.33.01 PM.png]]
 +
 
 +
This diagram shows the structure of how the arduino controlled the sensor to measure the height and also pass the reading of voltage to DAC which then being transfer to varactor for resonance frequency variation. The sensor that had been used is laser displacement sensor (LDS CP08MHT80)  which can give high resolution (8um), reasonable price and also give a good result of the measurement.
 +
 
 +
==Project Results==
 +
 
 +
From the simulation made in CST software, the graph of S2:1 which shows the frequency shift shown a successful improvement by 32% of normalised frequency shift from last year. This shows that when the MUT are placed under the SRR, the shift are more significant than before. Two MUT (copper and fr4) are used to compare from the last year result.
 +
 
 +
[[File:Resultvvvvpng.png]]
 +
 
 +
==Conclusion==
 +
 
 +
Based on the project result and system overview, the project are not 100% successful due to a few constraint. This project managed to increase frequency shift, replacing VNA with more compact device which is varactor and improved from 2 dimension mapping to 3 dimension mapping by adding z-axis reading. There are lot of improvement that can be made in future to make the project better and can be used in industry.
 +
 
 +
==Future Work==
 +
 
 +
1. Used a more expensive substrate to replace fr4 to decrease the loss of tangent so that the result of real test will not much different from the simulation.
 +
 
 +
2. Design 3D tip SRR which give better performance.

Latest revision as of 16:23, 18 October 2018

Introduction

Split Ring Resonator (SRR) is an electromagnetic metamaterial which can be used as a sensing device. This project is developed to produce a 2D permittivity mapping for different types of material under test (MUT). A device that used SRR as a sensing device is produced with a varactor to load the DC voltage to replace the Voltage Network Analyser (VNA) and 3 dimension testing of scanning system.

Gambarsystem.png

The figure shows how the system that is built from last project. This year, the project changed the system so that it will be more effective. The varactor is included to the SRR to replace the VNA and a new system that can provide 3D scanning is added to replace the 2D system made by last year project.

Project Group Members

1. Izatul Natasha Zulkefli

2. Liang Cheng

3. Ziyuan Wang

Project Supervisors

1. Dr. Withawat Withayachumnankul

2. Professor Christophe Fumeaux

Project Aims and Approached

The aim of this project is to make the SRR sensing device produced by the last year group to have higher sensitivity in scanning the MUT. There are three approached that been explore to increase the sensitivity of the sensing device using SRR.

1. Designing different design of SRR

Designing the SRR is the main part of the project for increasing of the sensitivity. This designing process had considered many types of factor so that the SRR can works well when tested with different types of MUT. The shape of SRR had been maintained from the previous shape which is in triangle shape as this shape can give better resolution . As for the design, the microstrip had been change to match with the 50 ohm characteristic impedance for impedance matching with the port. The SRR also were designed with almost no thickness so that it can give better resolution besides can made the varactor being soldiered easily on the SRR. Two inductance line were made to supply dc voltage and stopping the RF signal.

2. Load Varactor on the SRR

Varactor is a diode that can vary its capacitance by loading the DC voltage. This special characteristic made varactor suitable to replaced the VNA . VNA were used by the previous group to produced the change of the resonance shift when MUT are placed under the SRR. This function were replaced by varactor which vary the DC voltage to get the reading of the frequency shift.

3. 3 Dimension Sensing

The permittivity mapping are done by 2 dimension mapping by last year project. As to increase the permittivity mapping function, a system which allow 3 dimension mapping (x,y and z axis) were produced.

Project Design

Screen Shot 2018-10-18 at 1.55.36 PM.png


The cycle shows how the overview of the project structure. Starting with SRR as a sensing device to test with different MUT. Then, the system continue with the power detector getting the measurement of the power signal produced by the SRR. This power signal then being analysed by the arduino board which had coded to pass the reading of the power signal to the Digital Analog Converter. This reading were then received by the varactor to produce the result of frequency shift made by the SRR.


Design and Hardware

SRR


SRR were design as shown in figure below :

Screen Shot 2018-10-18 at 1.59.48 PM.png

Substrate  : Substrate that had been used is fr4 which has relative permittivity of 4.3.

Microstrip line  : Microstrip line with width of 3.162mm with almost no thickness were used to get the impedance characteristic of 50 ohm for impedance matching.

Varactor  : loaded on the SRR used for changing the resonance frequency.

Conductance line : Used for RF choke which supply DC voltage and stop the flowing of RF Signal.


Power Detector


Screen Shot 2018-10-18 at 2.18.33 PM.png

This power detector are used to measure the voltage amplitude produced by SRR.


DAC And Arduino


Screen Shot 2018-10-18 at 2.33.01 PM.png

This diagram shows the structure of how the arduino controlled the sensor to measure the height and also pass the reading of voltage to DAC which then being transfer to varactor for resonance frequency variation. The sensor that had been used is laser displacement sensor (LDS CP08MHT80) which can give high resolution (8um), reasonable price and also give a good result of the measurement.

Project Results

From the simulation made in CST software, the graph of S2:1 which shows the frequency shift shown a successful improvement by 32% of normalised frequency shift from last year. This shows that when the MUT are placed under the SRR, the shift are more significant than before. Two MUT (copper and fr4) are used to compare from the last year result.

Resultvvvvpng.png

Conclusion

Based on the project result and system overview, the project are not 100% successful due to a few constraint. This project managed to increase frequency shift, replacing VNA with more compact device which is varactor and improved from 2 dimension mapping to 3 dimension mapping by adding z-axis reading. There are lot of improvement that can be made in future to make the project better and can be used in industry.

Future Work

1. Used a more expensive substrate to replace fr4 to decrease the loss of tangent so that the result of real test will not much different from the simulation.

2. Design 3D tip SRR which give better performance.

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