Bravo MRI Network Analyzer Training from AEA Technology, Inc. For further assistance, visit our dedicated help desk at http://help.aeatech.com or send an email to techsupport@aeatechnology.com. You can also visit us online at http://aeatechnology.com.

1. Bravo MRI
Network Analyzers
Training

2. Presentation Table of Content
2
Bravo MRI models and accessories………………….. 3
About Vector Impedance analyzers…………………… 6
MRI Room Precautions………………………………… 11
Bravo MRI Operation…………………………………… 12
Bravo MRI and PC Software…………………………… 19
Summary…………………………………………………. 24
Cleaning and Maintenance…………………………….. 25
Warranty and Contact Information…………………….. 26
Questions and Acknowledgements…………………… 27

3. Bravo MRI models
Bravo MRI – Single BNC Port (S11)
Frequency Range 100KHz – 70MHz (0.1T to 1.5T MRIs)
Bravo MRI II – Dual N Ports (S11 & S21)
Frequency Range 100KHz – 200MHz (0.1T to 3.0T MRIs)
Bravo MRI II Kit – Dual BNC Ports (S11 & S21)
Frequency Range 100KHz – 200MHz (0.1T to 3.0T MRIs)
Adds Hard Carrying Case
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4. Bravo MRI Accessories
Belt Case Manual Quick Start Guide N Terminators
(Bravo MRI II)
BNC Terminators
(Bravo MRI &
Bravo MRI II Kit)
A/C Adapter
with 25ft (7.6m)
DC cord
Serial Cable
with 25ft (7.6m)
Cable
MRI
Interference
Filter
CD with:
Bravo PC Vision
Operating Manual
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5. Bravo MRI Optional Accessories
Hard Carrying
Case
Soft Carrying
Case
Coax Test Lead
50Ω BNC
Serial-to-USB
Adapter
N-to-BNC
Adapter
Certificate of Calibration
Certificate of Calibration with before and
after data
Note: These certificates must be ordered
with the instrument or the instrument must
be returned to our Calibration Laboratory
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6. Why Use a Vector
Impedance Analyzer?
 Scalars provide SWR & Return Loss information, but not
Vector Impedance. A high SWR reading doesn’t tell you
what to fix or what to tune in an MRI coil
 The VIA Bravo’s information can be used to:
Maximize an MRI Coil’s efficiency
Improve the MRI Machine’s image quality
Document a coil’s readings – electronic or paper media
Tune a coil installed or outside the MRI
 The VIA Bravo has “Cable Null” to remove the test lead
from the measurements
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7. What Chokes an MRI Coil
Resistance Inductance
Capacitance
Impedance Reactance
Frequency
Resonance
Impedance Angle Reflection Coefficient
All the factors for a coil’s performance MUST balance or the
result is Power Loss from increased VSWR in transmit coils
and reception loss in receive coils from out-of-phase current and
voltage and from impedance mismatches
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8. Vector Impedance and
the Right Hand Plane (RHP)
X = Reactance, Z = Total Impedance, R = Resistance,
θ = Z Angle, and i or j = square root of -1
Above, the positive X values plot into one quadrant of a
Cartesian graph’s RHP, negative X values plot in the other
quadrant directly below this one
8

9. Mapping the RHP to a unit circle
– Smith Chart
Note where Zo plots – Dead Center is Coil System Perfection
Inductive
ResistiveLow Z
High Z
Capacitive
9

10. ELI the ICE Man
For best performance an antenna should be purely
resistive and resonant near Zo at the center frequency
(Fc)
Power loss factors include:
If the antenna is inductive, voltage will lead current (ELI)
If the antenna is capacitive, current will lead voltage (ICE)
Either of these conditions exceeding the manufacturer’s
specifications require corrective action by tuning the
antenna or adding a tuning stub
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11. MRI Room Precautions
 All Bravo MRI models are slightly magnetic so use care in
and around the MRI’s core
 Operate using the AC Adapter and extended DC cord to power
the Bravo MRI from outside the room
 Do NOT use with batteries installed when in an MRI room.
They add significantly to the ferrous material
 Damage from being sucked in a core is NOT a warranty
repair. Warranty covers only factory defects not user
damage.
 Operating with the long serial cable permits operating in
remote control from a PC outside the MRI room
 Always use the MRI Filter to avoid erroneous readings
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12. Bravo MRI Operation
 Vector Impedance Analyzer
 Measures (S11 port):
SWR Return Loss
Total Z Z Angle
Resistance Reactance
Calculated Q
 S21 Ports: Gain Angle
Linear or Log Gain (Loss)
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13. Bravo MRI Keypad
Menu or Help
F2-Audio, Backlight,
Contrast, Cable
Null
F3-Plot Select, RLC
Model, Noise
Filter
F4-Grid, X Label,
Scales
F5-Save, Recall,
Plot Name,
Cable Zo, BAUD
F2
Audio – 4 Volume settings, On, Off, & Readout
Backlight – Off, 10,20,50 sweeps or Continuous
Backlight – Brightness Levels
LCD – Contrast, 16 Levels
Cable Null – ON or OFF
F3
Left Plot – (S11 or S21) Z, A, R, X, SWR, RL, G, P, L or none
Right Plot – (S11 or S21) Z, A, R, X, SWR, RL, G, P, L or none
RCL Model – Series or Parallel
Plot Width – 80 or 100 points
Big Frequency Display – ON or OFF
Noise Filter – ON or OFF
F4
Grid Lines – 1, 3, or 5
X Axis Label - +/- Delta F or absolute frequency
Plot 1 Scale – Choices vary with parameter
Plot 2 Scale – Choices vary with parameter
F5
Save – Enter 1 to 24 & Memory Name
Recall – Enter 1 to 24
Plot Name – Alpha-Numberic, 12 Characters
Cable Impedance – Numeric entry
Com Port BAUD – Recommend 52600
Self Test – Self Test Results and Keypad check
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14. Bravo MRI Keypad
Change the sweep
width up or down
 Numeric Entry and
up or down will enter
new width
Change the Center
Frequency by step size
 Numeric Entry & UP
New step size and
Increment Center Freq.
 Numeric Entry &
DOWN new step size
And decrement Center
Frequency.
 Numeric Entry and
Press to enter
new Center Frequency
Press to freeze
plot
Press again to
restart live plot
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15. Left = Unit of measure for selected test on Left vertical axis
Right = Unit of measure for selected test on Right vertical axis
FL>FC>FH = Frequency sweep range
FL = Lowest frequency of the sweep
FC = Center frequency of the sweep
FH = Highest frequency of the sweep
VIA Bravo
LCD Display
Bravo MRI
Q
Q = Coil’s Q
15

16. Q = The calculated “Q”
Bravo MRI
Q
R = Numeric readout for Right Plot (+++++) center frequency
measurement or in EXAM/PLOT the measurement at
the cursor frequency
L = Numeric readout for Left Plot ( ) center frequency.
In EXAM/PLOT the measurement at the cursor
frequency
16

17. A coil is resonant at the frequency(s) where
the Impedance (Phase) Angle is equal to zero (0).
Center Frequency
Right plot (thick)
= ө Angle of 2.38o
Left plot (thin)
= Z of 50.6Ώ at
resonance
Positive ө Angle
= inductive coil
Negative ө Angle
= capacitive coil
Smith Chart
Bravo MRI
Q
100
17

18. Frequency Sweep vs CW Mode
Frequency Sweep
Normal Mode
One sweep about every second from FL to FH
Tuning requires a 1-2 seconds wait for change to post
Continuous Wave Mode (Set Bandwidth to zero)
Update rate is increased to about 2.5 times per second
CW operates at Center Frequency – no sweep
Tuning changes appear almost instantly
Tuning by the numbers is faster
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19. VIA Bravo MRI & PC Software
 Operates on Microsoft Windows XP® Win 7® and Win 8®
 Included with the Bravo MRI models and available on our
web site at www.aeatechnology.com
 No license required. Load on an number of PCs
 Win 7 and Win8 require “PV.INI” file installed
 PCs with no serial port will require a Serial-to-USB Adapter
AEA Technology P/N 0070-1216
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20. VIA Bravo MRI & PC Software
S-11 Port
 Impedance
 Impedance Angle
 Resistance
 Reactance
 VSWR
 Return Loss
 Smith Chart*
S21 Port
 Reflection Coefficient
Magnitude
Angle
 Gain (Loss)
Linear
Log
Save, Print, Email Plots, etc*
*In the Bravo PC Vision software which is included
20

21. Bravo PC Vision
21

22. Smith Chart from Antenna Sweep
As the frequency changes the coil’s reactance moves from
inductive to capacitive with some impedance change and is
resonant slightly off the center of the swept frequency
22

23. Bravo PC Vision Software
 Upload Current or Stored Plots from the VIA
Bravo MRI
 Chart 8 Parameters at once
 Save Charts on a PC or on CDs
 Export Charts – (BMP, JPEG, GIF or TIFF)
 Produce Smith Charts
 Print Charts
 Create a Records data base and provide coil
documentation to customers
23

24. Summary
 Proper coil tuning provides the clearest MRI images
Scalars provide only SWR and Return Loss, but NOT
resonance information. Proper coil tuning or
diagnostic work requires a network analyzer
The Bravo MRI is 100KHz to 70MHz (0.1 to 1.5T) VNA
The Bravo MRI II is 100KHz to 200MHz (0.1 to 3.0T) VNA
The Bravo MRI displays any two parameters at once, but
stores all six or eight parameters measured
Bravo PC Vision will display all eight parameters at once
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25. Cleaning Your Bravo MRI
1. Always spray cleaners and rinse water on a soft cloth, do NOT
spray directly on the TDR
Soft Cases
The soft case should be cleaned the same as the instrument. Use
a soft bush to remove tough dirt. Do NOT immerse in water or dry
in a dryer. Wash and Dry separately, both instrument and case should
be dry before enclosing the instrument in the case.
2. Typical Grime – Use a mild non-abrasive detergent like 409®
in
water or glass cleaner (non-ammonia) and rinse water to clean
3. Cable Gel – User liquid “citrus” cleaner to remove
4. Tar, creosote or adhesives – Use WD40® followed with mild
detergent and water
25

26. Maintenance, Service and Warranty
Operator Manual, Maintenance, Service & Warranty.
Warranty – One year against material & workmanship defects
Questions, By all means – Contact us:
AEA Technology, Inc.
5933 Sea Lion Place, Ste 112
Carlsbad, CA 92010
Tel: 800-258-7805 or +1-760-931-8979
Fax: +1-760-931-8969
www.aeatechnology.com
Email
Application Notes
Operating Manuals
Bravo PC Vision
Data Sheets
See “User Troubleshooting Guide”
26

27. Questions
on
Bravo MRI or MRI II
Bravo PC Vision software?
Windows XP, Vista, Windows 7 and Windows 8 are registered trademarks of Microsoft®
Corp.
409 is a registered trademark of Clorox®
Corp.
WD-40 is a registered trademark of WD-40® company
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