Low Cost, Compact Microwave Reflectometer for Non-Destructive Testing

Matthew Rangen and Keith Bruno

April 15, 2005

Bradley UniversityDepartment of Electrical and Computer Engineering

Overview

• Objective• Background• Block Diagram• Tasks & Schedule• Results

• MATLAB• Network Analyzer

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.

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.

Detailed Block Diagram

Tasks & Schedule Matthew Rangen Keith Bruno

January 21 to 27 Develop Calibration & Measuring Equations

Design & Simulate 90º Hybrid

Jan/Feb 28 to 3 · · February 4 to 10 · 11 to 17 Implement Equations in MATLAB

Design & Simulate Lange Coupler

18 to 24 · · Feb/March 25 to 3 · Design & Simulate 6-port March 4 to 10 Test Programming Code · 11 to 17 Spring Break 18 to 24 · Fabricate 6-port Parts 25 to 31 Integrate MATLAB & Oscilloscopes Fabricate 6-port April 1 to 7 Purchase Detectors 8 to 14 Test 6-port 15 to 21 System Integration & Testing 22 to 28 Final Report & Presentation Preparation April/May 29 to 5 Final Report due, Presentation & Final Exams May 6 to11 Final Exams

Calibration Process

The Calibration process is used to find the complex numbers:

These numbers are used to find the gamma of an unknown load.

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.

Calibration Process

By taking the power measurements:

Calibration Process

By taking the gammas:

Calibration Process

Now by combining the two previous steps.

+

The calibration process then begins to solve:

MATLAB Work

CalibrationFlowchart

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.

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.

MATLAB Work

MeasureFlowchart

6-Port Network Analyzer

TermTerm2Z=50 Ohm

DA_BLCoupler_untitled1DA_BLCoupler4

C=3 dBF=5.15 GHz

DA_BLCoupler_untitled1DA_BLCoupler3

C=3 dBF=5.15 GHz

DA_BLCoupler_untitled1DA_BLCoupler2

C=3 dBF=5.15 GHz

DA_BLCoupler_untitled1DA_BLCoupler1

C=3 dBF=5.15 GHz

P_1TonePORT2

Freq=6 GHzP=dbmtow(10)

MSUBMSub1

Rough=0.0948 milTanD=0.0013T=1.4 milHu=3.9e+34 milCond=5.8E+7Mur=1Er=3.0H=30 mil

MSub

HarmonicBalanceHB1

Order[1]=10Freq[1]=1.0 GHz

HARMONIC BALANCE

TermTerm1Z=50 Ohm

RR1R=50 Ohm

DA_LCoupler_untitled1DA_LCoupler1

N=4C=6 dBF=6 GHz

P_one

P_two P_three

P_four

90° Hybrid

Input Port Output Port

Isolated Port Output Port

}90° phase-shift

difference

90° Hybrid

TermTerm3

Z=50 OhmNum=3

MLINTL16

L=3.2029 cmW=0.127701 cmSubst="MSub1"

MLINTL15

L=3.2029 cmW=0.127701 cmSubst="MSub1"

TermTerm4

Z=50 OhmNum=4

S_ParamSP1

Step=1.0 MHzStop=8.0 GHzStart=4.0 GHz

S-PARAMETERS

MSUBMSub1

Rough=0.0948 milTanD=0.0013T=1.4 milHu=3.9e+34 milCond=5.8E+7Mur=1Er=3.0H=20.0 mil

MSub

MLINTL14

L=3.2029 cmW=0.127701 cmSubst="MSub1"

TermTerm2

Z=50 OhmNum=2

MLINTL1

L=3.2029 cmW=0.127701 cmSubst="MSub1"

TermTerm1

Z=50 OhmNum=1

MLINTL18

L=0.785475 cmW=0.211619 cmSubst="MSub1"

MLINTL2

L=0.785475 cmW=0.211619 cmSubst="MSub1"

MLINTL17

L=0.800725 cmW=0.127701 cmSubst="MSub1"

MLINTL7

L=0.800725 cmW=0.127701 cmSubst="MSub1"

MTEE_ADSTee4

W3=0.211619 cmW2=0.127701 milW1=0.127701 cmSubst="MSub1"

MTEE_ADSTee3

W3=0.127701 cmW2=0.127701 cmW1=0.211619 cmSubst="MSub1"

MTEE_ADSTee2

W3=0.127701 cmW2=0.127701 cmW1=0.211619 cmSubst="MSub1"

MTEE_ADSTee1

W3=0.211619 cmW2=0.127701 cmW1=0.127701 cmSubst="MSub1"

90° Hybrid Results

4.5 5.0 5.5 6.0 6.5 7.0 7.54.0 8.0

-45

-40

-35

-30

-25

-20

-15

-10

-5

-50

0

freq, GHz

dB(S

(1,1

))dB

(S(1

,2))

dB(S

(1,3)

)dB

(S(1

,4))

90° Hybrid Results

Eqn ph=phase(S(1,4))-phase(S(1,3))

m3freq=m3=-272.650

6.000GHz

m4freq=m4=89.996

6.704GHz

m3freq=m3=-272.650

6.000GHz

m4freq=m4=89.996

6.704GHz

4.5 5.0 5.5 6.0 6.5 7.0 7.54.0 8.0

-250

-200

-150

-100

-50

0

50

100

-300

150

freq, GHz

ph

Readout

m3

Readout

m4

90° Hybrid

DA_BLCoupler1_nineDA_BLCoupler1

C=3 dBF=5.15 GHz

MSUBMSub1

Rough=0.0948 milTanD=0.0013T=1.4 milHu=3.9e+34 milCond=5.8E+7Mur=1Er=3.0H=30 mil

MSub

90° Hybrid

PortP4Num=4

PortP3Num=3

PortP2Num=2

PortP1Num=1

MTEETee4

W3=1.927 mmW2=3.188 mmW1=1.92 mmSubst="MSub1"

MLINTL4

L=7.188 mmW=3.188 mmSubst="MSub1"

MTEETee3

W3=1.927 mmW2=1.92 mmW1=3.188 mmSubst="MSub1"

MLINTL3

L=6.115 mmW=1.927 mmSubst="MSub1"

MLINTL2

L=6.115 mmW=1.927 mmSubst="MSub1"

MTEETee2

W3=1.927 mmW2=1.92 mmW1=3.188 mmSubst="MSub1"

MLINTL1

L=7.188 mmW=3.188 mmSubst="MSub1"

MTEETee1

W3=1.927 mmW2=3.188 mmW1=1.92 mmSubst="MSub1"

90° Hybrid Results

3 4 5 6 7 8 92 10

-35

-30

-25

-20

-15

-10

-5

-40

0

freq, GHz

S (d

B)

S11S21S31S41 C

3.00C(dB)=

Lange Coupler

Coupled Port

Through Port

Input Port

Isolated Port

Lange Coupler

DA_LCoupler1_langeDA_LCoupler1

N=4C=6 dBF=6 GHz

MSUBMSub1

Rough=0.0948 milTanD=0.0013T=1.4 milHu=3.9e+34 milCond=5.8E+7Mur=1Er=3.0H=30 mil

MSub

Lange Coupler

PortP4Num=4

PortP3Num=3

PortP2Num=2

PortP1Num=1

MLANGLang1

L=8.46 mmS=0.228 mmW=0.423 mmSubst="MSub1"

Lange Coupler Results

3 4 5 6 7 8 92 10

-45-40-35-30-25-20-15-10-5

-50

0

freq, GHz

S (d

B)

S11S21S31S41 C

6.00C(dB)=

Overview

• Objective• Background• Block Diagram• Tasks & Schedule• Results

• MATLAB• Network Analyzer

Questions?

Check us out at:

cegt201.bradley.edu/projects/proj2005/sixpna

Calibration Work

Calibration FlowEquations

Calibration Work

Calibration Flow Equations Part 2

Calibration Work

Calibration Flow Equations Part 3

Measurement Work

Measurement Equations