Low Cost, Compact Microwave Reflectometer for NonDestructive Testing

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Low Cost, Compact Microwave Reflectometer for
Non-Destructive Testing

• Matthew Rangen and Keith Bruno
• April 15, 2005
• Bradley University
• Department of Electrical and Computer Engineering

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Overview

• Objective
• Background
• Block Diagram
• Tasks Schedule
• Results
• MATLAB
• Network Analyzer

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Objective
The objective of the project is to determine the
reflection coefficient of an unknown load by the
use of a six-port network analyzer integrated
with a workstation.
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Background
The reflection coefficient can be found by
knowing a reference signal and sampling selected
power outputs in a micro-strip circuit. With
these known quantities and using a specific
algorithm, the reflection coefficient can be
calculated.
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Detailed Block Diagram
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Tasks Schedule
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Calibration Process
The Calibration process is used to find the
complex numbers
These numbers are used to find the gamma of an
unknown load.
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Calibration Process
The Calibration process needs two known items to
start the process.
1. Gammas of the Known Loads
2. Power Measurements of the Known Loads
Once this is known the calibration process may
begin.
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Calibration Process
By taking the power measurements
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Calibration Process
By taking the gammas
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Calibration Process
Now by combining the two previous steps.

The calibration process then begins to solve
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MATLAB Work
Calibration Flowchart
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Measurement Process
By using the the known complex numbers found from
the calibration process, any gamma can be
calculated from an unknown load.
This process is very simple compared to the
calibration process.
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Measurement Process
The measurement process needs only one known
item.
1. Power Measurements from the unknown load
Once this is known, the measurement process
begins.
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MATLAB Work
Measure Flowchart
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6-Port Network Analyzer
P_two
P_three
P_four
P_one
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90 Hybrid

Input Port
Output Port
90 phase-shift difference
Isolated Port
Output Port
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90 Hybrid
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90 Hybrid Results
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90 Hybrid Results
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90 Hybrid
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90 Hybrid
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90 Hybrid Results
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Lange Coupler
Through Port
Isolated Port
Coupled Port
Input Port
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Lange Coupler
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Lange Coupler
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Lange Coupler Results
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Overview

• Objective
• Background
• Block Diagram
• Tasks Schedule
• Results
• MATLAB
• Network Analyzer

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Questions? Check us out at cegt201.bradley.edu
/projects/proj2005/sixpna
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Calibration Work
Calibration Flow Equations
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Calibration Work
Calibration Flow Equations Part 2
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Calibration Work
Calibration Flow Equations Part 3
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Measurement Work
Measurement Equations