Bravo MRINetwork Analyzers

Training

Presentation Table of Content

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

Bravo MRI modelsBravo 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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Bravo MRI Accessories

Belt Case Manual Quick Start Guide N Terminators (Bravo MRI II)

BNC Terminators (Bravo MRI & Bravo MRI II Kit)

A/C Adapterwith 25ft (7.6m)

DC cord

Serial Cablewith 25ft (7.6m)

Cable

MRI Interference

Filter

CD with: Bravo PC Vision Operating Manual

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Bravo MRI Optional Accessories

Hard CarryingCase

Soft CarryingCase

Coax Test Lead50Ω BNC

Serial-to-USBAdapter

N-to-BNCAdapter

Certificate of Calibration Certificate of Calibration with before and after dataNote: These certificates must be ordered with the instrument or the instrument must be returned to our Calibration Laboratory

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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 efficiencyImprove the MRI Machine’s image qualityDocument a coil’s readings – electronic or paper mediaTune a coil installed or outside the MRI

The VIA Bravo has “Cable Null” to remove the test leadfrom the measurements

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What Chokes an MRI Coil

Resistance InductanceCapacitance

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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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 one8

Mapping the RHP to a unit circle – Smith Chart

Note where Zo plots – Dead Center is Coil System Perfection

Inductive

ResistiveLow ZHigh Z

Capacitive

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ELI the ICE ManFor 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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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 userdamage.

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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Bravo MRI Operation Vector Impedance Analyzer Measures (S11 port):

SWR Return LossTotal Z Z AngleResistance ReactanceCalculated Q

S21 Ports: Gain AngleLinear or Log Gain (Loss)

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Bravo MRI KeypadMenu or HelpF2-Audio, Backlight, Contrast, Cable NullF3-Plot Select, RLC Model, Noise FilterF4-Grid, X Label, ScalesF5-Save, Recall, Plot Name, Cable Zo, BAUD

F2Audio – 4 Volume settings, On, Off, & ReadoutBacklight – Off, 10,20,50 sweeps or ContinuousBacklight – Brightness LevelsLCD – Contrast, 16 LevelsCable Null – ON or OFF

F3Left 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 noneRCL Model – Series or ParallelPlot Width – 80 or 100 pointsBig Frequency Display – ON or OFFNoise Filter – ON or OFF

F4Grid Lines – 1, 3, or 5X Axis Label - +/- Delta F or absolute frequencyPlot 1 Scale – Choices vary with parameterPlot 2 Scale – Choices vary with parameter

F5Save – Enter 1 to 24 & Memory NameRecall – Enter 1 to 24Plot Name – Alpha-Numberic, 12 CharactersCable Impedance – Numeric entryCom Port BAUD – Recommend 52600Self Test – Self Test Results and Keypad check

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Bravo MRI KeypadChange the sweepwidth up or down Numeric Entry andup or down will enternew width

Change the CenterFrequency by step size Numeric Entry & UPNew step size and Increment Center Freq. Numeric Entry &DOWN new step sizeAnd decrement CenterFrequency.

Numeric Entry andPress to enternew Center Frequency

Press to freeze plotPress again to restart live plot

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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 rangeFL = Lowest frequency of the sweep

FC = Center frequency of the sweep FH = Highest frequency of the sweep

VIA Bravo LCD Display

VIA Bravo

R +++

L/C

LLeft Right

FCFL FH

00.0

00.0

00.0

Bravo MRI

Q

Q = Coil’s Q

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Q = The calculated “Q”

VIA Bravo

R +++

L/C

LLeft Right

FCFL FH

00.0

00.0

00.0

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

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VIA Bravo

R +++

L/C

L 50.6

2.38

19.7LNH

200 OHMS

0

DEGREES 90

90

+0-

FC = 21.000 MHZ-6.40M +6.40M

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 coilNegative ө Angle= capacitive coil

Smith Chart

Bravo MRI

Q 100

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Frequency Sweep vs CW ModeFrequency Sweep

Normal ModeOne sweep about every second from FL to FHTuning 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 secondCW operates at Center Frequency – no sweepTuning changes appear almost instantlyTuning by the numbers is faster

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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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VIA Bravo MRI & PC SoftwareS-11 Port Impedance Impedance Angle Resistance Reactance VSWR Return Loss Smith Chart*

S21 Port Reflection Coefficient

MagnitudeAngle

Gain (Loss) Linear

LogSave, Print, Email Plots, etc*

*In the Bravo PC Vision software which is included

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Bravo PC Vision

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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

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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

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 once24

Cleaning Your Bravo MRI1. Always spray cleaners and rinse water on a soft cloth, do NOT

spray directly on the TDR

Soft CasesThe soft case should be cleaned the same as the instrument. Usea soft bush to remove tough dirt. Do NOT immerse in water or dryin a dryer. Wash and Dry separately, both instrument and case shouldbe 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 clean3. Cable Gel – User liquid “citrus” cleaner to remove4. Tar, creosote or adhesives – Use WD40® followed with mild

detergent and water

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Maintenance, Service and WarrantyOperator 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 112Carlsbad, CA 92010Tel: 800-258-7805 or +1-760-931-8979Fax: +1-760-931-8969

www.aeatechnology.comEmail

Application Notes

Operating Manuals

Bravo PC Vision

Data Sheets

See “User Troubleshooting Guide”

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Questionson

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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