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Bravo MRI Network Analyzer Training

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Bravo MRI Network Analyzer Training

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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.

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.

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Bravo MRI Network Analyzer Training

  1. 1. Bravo MRI Network Analyzers Training
  2. 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. 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 3
  4. 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 4
  5. 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 5
  6. 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 6
  7. 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 7
  8. 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. 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. 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 10
  11. 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 11
  12. 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) 12
  13. 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 13
  14. 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 14
  15. 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. 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. 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. 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 18
  19. 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 19
  20. 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. 21. Bravo PC Vision 21
  22. 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. 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. 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 24
  25. 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. 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. 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 27

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