RHUL Physics Department TWiki> PP/JAI Web>RFLab>BeamPosition>AtfBpmDigital>AtfBpmNewLogBook>AtfBpmNewLogBook_20111212_cavityDiodeProgress (09 Apr 2013, YoungimKim)
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Cable loss measurement

  • Source offset, connected source via BPM cable to power meter
Frequency (MHz) $P_{set}$ (dBm) $P_{out}$ (dBm)
6500 -10 -10.46
0 -0.4
25 0 -0.01

  • Inject 0 dBm at tunnel into heliax, measured at end of heliax
Cable Output Power
Number 6500MHz 25MHz
10 -24.08 -1.36
11 -24.2 -1.3
12 -24.37 -1.33

  • Loss for scope (SMA to LEMO, LEMO to BNC) cable ; ~1.5m
Frequency (MHz) $P_{in}$ dBm $P_{out}$ dBm
6500 0 -5.77
25 0 -0.4

X-Y position scans.

  • Cable arrangement is in following order: Cavity --> Coaxial cable (1 ft) --> diode --> Heiax coaxial cable with N-type to SMA adapter --> SMA to LEMO cable with LEMO to BNC adapter --> scope

CableToScopeConnection_forpresentation.png

  • Diode calibration at different output load resistance.
DiodeCalibration_DiodeResponse_dB.png DiodeCalibration_DiodeResponse.png
DiodeCalibration_voltPowRadioVsInputPower.png DiodeCalibration_voltPowRadioVsOutputvolt.png

  • Diode sensitivity used for 50 ohm termination= -15 mV/mW
  • Equation used for parabola fitting is $(x-x_0)^2 \times S = (P - P_0) $
  • Voltage sensitivity $V_{in,diode} = (P_{in,diode} \times 50)^{0.5}$
  • $V_{offset} = \frac{\omega}{2}\, \sqrt{\frac{Z}{Q_{ext}} \left(\frac{R}{Q_0}\right)_{1mm}} ,q\,\frac{x}{1mm}\, exp\left(-\frac{\sigma^2\omega^2}{2c^2}\right)\, TT $

Parameter (X & Y) Value
Frequency 6372 & 6377 MHz
Z 50 ohm
$ Q_{ext} $ 13400 & 18000
$\sigma $ 8 mm
$(R/Q_0)$ (from simulation) 0.8 & 0.8 ohm/mm
$ q $ 1.6 nC
Offset $ x $ 1 mm
TT 0.85
$V_{offset}$ (V/1mm) 0.804 & 0.691

X position scan.

Cavity moved in X on 20111215_02.

DiodeInputPower_X_20111215_02.png DiodeInputVoltage_X_20111215_02.png

Cavity moved in X on 20111215_03

DiodeInputPower_X_20111215_03.png DiodeInputVoltage_X_20111215_03.png

Y position scan.

Cavity moved in Y on 20111213:

DiodeInputPower_Y_20111213.png DiodeInputVoltage_Y_20111213.png

Cavity moved in Y on 20111215

DiodeInputPower_Y_20111215.png DiodeInputVoltage_Y_20111215.png

Attachments Attachments
Topic attachments
I Attachment History Action Size Date Who Comment
PNGpng CableToScopeConnection_forpresentation.png r1 manage 2526.5 K 15 Jan 2012 - 21:26 NiravJoshi  
PNGpng DiodeCalibration_DiodeResponse.png r3 r2 r1 manage 29.5 K 22 Feb 2012 - 23:29 NiravJoshi  
PNGpng DiodeCalibration_DiodeResponse_dB.png r1 manage 31.0 K 22 Feb 2012 - 23:30 NiravJoshi  
PNGpng DiodeCalibration_voltPowRadioVsInputPower.png r1 manage 37.8 K 23 Feb 2012 - 15:26 NiravJoshi  
PNGpng DiodeCalibration_voltPowRadioVsOutputvolt.png r1 manage 27.0 K 23 Feb 2012 - 15:27 NiravJoshi  
PNGpng DiodeInputPower_X_20111215_02.png r3 r2 r1 manage 30.0 K 22 Feb 2012 - 10:43 NiravJoshi  
PNGpng DiodeInputPower_X_20111215_03.png r3 r2 r1 manage 30.6 K 22 Feb 2012 - 10:44 NiravJoshi  
PNGpng DiodeInputPower_Y_20111213.png r3 r2 r1 manage 32.4 K 22 Feb 2012 - 10:44 NiravJoshi  
PNGpng DiodeInputPower_Y_20111215.png r3 r2 r1 manage 31.8 K 22 Feb 2012 - 10:45 NiravJoshi  
PNGpng DiodeInputVoltage_X_20111215_02.png r3 r2 r1 manage 27.4 K 22 Feb 2012 - 10:43 NiravJoshi  
PNGpng DiodeInputVoltage_X_20111215_03.png r3 r2 r1 manage 29.0 K 22 Feb 2012 - 10:44 NiravJoshi  
PNGpng DiodeInputVoltage_Y_20111213.png r3 r2 r1 manage 30.7 K 22 Feb 2012 - 10:45 NiravJoshi  
PNGpng DiodeInputVoltage_Y_20111215.png r3 r2 r1 manage 29.9 K 22 Feb 2012 - 10:45 NiravJoshi  
PNGpng PositionScan_CavityDiode_X_20111212.png r2 r1 manage 27.7 K 12 Dec 2011 - 12:49 NiravJoshi  
PNGpng PositionScan_CavityDiode_X_20111215.png r1 manage 28.4 K 15 Dec 2011 - 09:07 NiravJoshi  
PNGpng PositionScan_CavityDiode_Y_20111212.png r3 r2 r1 manage 28.7 K 12 Dec 2011 - 13:34 NiravJoshi  
PNGpng PositionScan_CavityDiode_Y_20111213.png r1 manage 29.9 K 15 Dec 2011 - 09:07 NiravJoshi  
PNGpng screenshot_ch25mVpdig_ch50mVpdiv_50nspdiv_50ohm.png r1 manage 63.7 K 12 Dec 2011 - 07:09 NiravJoshi  
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Topic revision: r15 - 09 Apr 2013 - YoungimKim

 
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