Difference: ClicProtoRF (1 vs. 9)

Revision 921 Aug 2014 - JackTowler

Line: 1 to 1
 
META TOPICPARENT name="NewClicBpm"

Reference Cavity

Line: 76 to 76
 
S11 14.988 1733 7888 1421 1420
S22 14.991 2026 6246 1537 1530
S33 14.988 1713 8327 1427 1421
Changed:
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<
S44 14/991 1647 13628 1462 1469
>
>
S44 14.991 1647 13628 1462 1469
 
  • The external Q is much higher than the design value of ~600, possibly caused by the incorrect coupler.

Revision 802 Jul 2014 - JackTowler

Line: 1 to 1
 
META TOPICPARENT name="NewClicBpm"

Reference Cavity

Line: 19 to 19
 
  • Simulations need to be performed to see if this effect is reproduced.
  • The Q values can be determined by plotting a smith chart.
Deleted:
<
<
short.png
  RefSmithFinal.png

S Parameter Frequency /GHz Unloaded Q External Q Loaded Q Loaded Q check
S11 14.698 382 588 231 231
S22 14.699 426 530 238 236
Added:
>
>
  • The unloaded Q factor is much smaller than expected, bringing the loaded Q down.
  • This could be caused by uneven clamping or not clamping strong enough or by excessive surface roughness.
  • The frequency and Q factor was seen to vary with antenna offset, so the effect of this offset needs to be investigated.
 

Feedthrough Offset Variation

  • Simulations were performed with the feedthrough offset 1 degrees the along the beam pipe direction.
Line: 42 to 44
 
1.0 14.780 2722 230 212
1.5 14.794 2715 260 237
Added:
>
>
OffsetSim.png

  • The frequency change depending on the antenna offset is ~700MHz/mm.
  • The Q factor change is not enough to explain the low loaded Q factor of the position cavity.
 

Dipole Mode

dipole.png

Line: 54 to 61
 
  • The BPM was clamped as above and all four ports connected to the VNA.
  • A drop in frequency from 15 MHz was predicted from simulation.
Changed:
<
<
refl.png
>
>
trans.png

S Parameter Frequency /GHz Loaded Q
S13 14.988 1434
S24 14.991 1545

  • The frequencies are very close to the expected value of 14.985 GHz, the Q factors are three times larger.
  • The coupling here is too weak to rely on the Q factors calculated from the Smith chart but it does offer clues to the source of the high loaded Q.

PosSmith.png

 
Changed:
<
<
S Parameter S11 S22 S33 S44
Frequency /GHz 14.988 14.991 14.988 14.991
>
>
S Parameter Frequency /GHz Unloaded Q External Q Loaded Q Loaded Q check
S11 14.988 1733 7888 1421 1420
S22 14.991 2026 6246 1537 1530
S33 14.988 1713 8327 1427 1421
S44 14/991 1647 13628 1462 1469

  • The external Q is much higher than the design value of ~600, possibly caused by the incorrect coupler.

Position Cavity with Reference Cavity Antenna

  • The position cavity was simulated with the feedthrough antenna from the reference cavity.

Frequency /GHz Unloaded Q External Q Loaded Q
14.983 3309 3192 1625

  • In the simulation the external Q is much larger than expected, driving the loaded Q up.
  • The value of the loaded Q is closer to that measured from the transmission curves.
  • This is encouraging evidence that using the correct feedthroughs and vacuum seal will results in Q's close to the design values.
 

Cross Coupling

Line: 66 to 98
 
S Parameter S21 S32 S43 S14
Maximum Signal /dB -30.9 -31.0 -39.8 -36.8
Added:
>
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  • All maximum cross couplings are below -30 dB.
 

Revision 730 Jun 2014 - JackTowler

Line: 1 to 1
 
META TOPICPARENT name="NewClicBpm"

Reference Cavity

Line: 27 to 27
 
S11 14.698 382 588 231 231
S22 14.699 426 530 238 236
Added:
>
>

Feedthrough Offset Variation

  • Simulations were performed with the feedthrough offset 1 degrees the along the beam pipe direction.
  • Corresponding to a antenna tip movement range of 0.26 mm within the cavity.
  • Positive values correspond to offsets towards the flat surface of the cavity, negative values correspond to offsets towards the reentrant part of the cavity.

Offset Angle /degrees Frequency /GHz Q_0 Q_ext Q_L
-1.5 14.736 2739 203 189
-1.0 14.743 2732 194 181
-0.5 14.751 2730 193 180
0.0 14.760 2727 197 184
0.5 14.771 2724 210 195
1.0 14.780 2722 230 212
1.5 14.794 2715 260 237
 

Dipole Mode

dipole.png

Revision 630 Jun 2014 - JackTowler

Line: 1 to 1
 
META TOPICPARENT name="NewClicBpm"

Reference Cavity

Line: 8 to 8
 

Monopole Mode

Changed:
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<
refrefl.png
>
>
RefTrans.png
 
Changed:
<
<
S Parameter S11 S22
Frequency /GHz 14.698 14.699
>
>
S Parameter S12 S21
Frequency /GHz 14.699 14.698
Loaded Q 235 235
 
  • The measured resonant frequency is 300 MHz below the desired 15 GHz.
  • The feedthrough antennae were not well concentrically aligned and frequency was seen to vary on repeated repositioning of the feedthrough.
  • Simulations need to be performed to see if this effect is reproduced.
  • The Q values can be determined by plotting a smith chart.
Added:
>
>
short.png
  RefSmithFinal.png

S Parameter Frequency /GHz Unloaded Q External Q Loaded Q Loaded Q check
Line: 62 to 65
 
META FILEATTACHMENT attachment="refrefl.png" attr="h" comment="" date="1403794368" name="refrefl.png" path="refrefl.png" size="50987" user="ztap061" version="1"
META FILEATTACHMENT attachment="dipole.png" attr="h" comment="" date="1403870901" name="dipole.png" path="dipole.png" size="47374" user="ztap061" version="1"
META FILEATTACHMENT attachment="RefSmithFinal.png" attr="h" comment="" date="1403877781" name="RefSmithFinal.png" path="RefSmithFinal.png" size="88686" user="ztap061" version="3"
Added:
>
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META FILEATTACHMENT attachment="RefTrans.png" attr="h" comment="" date="1404119569" name="RefTrans.png" path="RefTrans.png" size="42071" user="ztap061" version="1"

Revision 527 Jun 2014 - JackTowler

Line: 1 to 1
 
META TOPICPARENT name="NewClicBpm"

Reference Cavity

Line: 48 to 48
 
S Parameter S21 S32 S43 S14
Maximum Signal /dB -30.9 -31.0 -39.8 -36.8
Changed:
<
<
-- JackTowler - 26 Jun 2014

short.png

trans.png

>
>
<--

Settings just to customise this page

-->
 
META FILEATTACHMENT attachment="short.png" attr="h" comment="" date="1403787681" name="short.png" path="short.png" size="66660" user="ztap061" version="1"
META FILEATTACHMENT attachment="trans.png" attr="h" comment="" date="1403787681" name="trans.png" path="trans.png" size="58687" user="ztap061" version="1"

Revision 427 Jun 2014 - JackTowler

Line: 1 to 1
 
META TOPICPARENT name="NewClicBpm"

Reference Cavity

Line: 16 to 16
 
  • The measured resonant frequency is 300 MHz below the desired 15 GHz.
  • The feedthrough antennae were not well concentrically aligned and frequency was seen to vary on repeated repositioning of the feedthrough.
  • Simulations need to be performed to see if this effect is reproduced.
Added:
>
>
  • The Q values can be determined by plotting a smith chart.

RefSmithFinal.png

S Parameter Frequency /GHz Unloaded Q External Q Loaded Q Loaded Q check
S11 14.698 382 588 231 231
S22 14.699 426 530 238 236
 

Dipole Mode

Line: 55 to 60
 
META FILEATTACHMENT attachment="cc.png" attr="h" comment="" date="1403787681" name="cc.png" path="cc.png" size="82812" user="ztap061" version="1"
META FILEATTACHMENT attachment="refrefl.png" attr="h" comment="" date="1403794368" name="refrefl.png" path="refrefl.png" size="50987" user="ztap061" version="1"
META FILEATTACHMENT attachment="dipole.png" attr="h" comment="" date="1403870901" name="dipole.png" path="dipole.png" size="47374" user="ztap061" version="1"
Added:
>
>
META FILEATTACHMENT attachment="RefSmithFinal.png" attr="h" comment="" date="1403877781" name="RefSmithFinal.png" path="RefSmithFinal.png" size="88686" user="ztap061" version="3"

Revision 327 Jun 2014 - JackTowler

Line: 1 to 1
 
META TOPICPARENT name="NewClicBpm"

Reference Cavity

Line: 6 to 6
 
  • The BPM was clamped together and the feedthroughs also clamped without the vacuum seals so the separation was increased by 0.45 mm.
  • The VNA was connected to the two ports of the reference cavity where S parameters could be measured.
Added:
>
>

Monopole Mode

 refrefl.png

S Parameter S11 S22
Line: 15 to 17
 
  • The feedthrough antennae were not well concentrically aligned and frequency was seen to vary on repeated repositioning of the feedthrough.
  • Simulations need to be performed to see if this effect is reproduced.

Added:
>
>

Dipole Mode

dipole.png

S Parameter Frequency /GHz Loaded Q
S11 19.090 98
 

Position Cavity

  • The BPM was clamped as above and all four ports connected to the VNA.
Line: 43 to 54
 
META FILEATTACHMENT attachment="refl.png" attr="h" comment="" date="1403794368" name="refl.png" path="refl.png" size="67704" user="ztap061" version="3"
META FILEATTACHMENT attachment="cc.png" attr="h" comment="" date="1403787681" name="cc.png" path="cc.png" size="82812" user="ztap061" version="1"
META FILEATTACHMENT attachment="refrefl.png" attr="h" comment="" date="1403794368" name="refrefl.png" path="refrefl.png" size="50987" user="ztap061" version="1"
Added:
>
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META FILEATTACHMENT attachment="dipole.png" attr="h" comment="" date="1403870901" name="dipole.png" path="dipole.png" size="47374" user="ztap061" version="1"

Revision 226 Jun 2014 - JackTowler

Line: 1 to 1
 
META TOPICPARENT name="NewClicBpm"
Changed:
<
<

RF Tests at RHUL

Reference Cavity

>
>

Reference Cavity

 
  • The dimensions of the first copper prototype were known to be incorrect. Predicting a frequency drop of ~330 MHz and a loaded Q drop of 160.
  • The BPM was clamped together and the feedthroughs also clamped without the vacuum seals so the separation was increased by 0.45 mm.
  • The VNA was connected to the two ports of the reference cavity where S parameters could be measured.

Changed:
<
<

Position Cavity

>
>
refrefl.png

S Parameter S11 S22
Frequency /GHz 14.698 14.699

  • The measured resonant frequency is 300 MHz below the desired 15 GHz.
  • The feedthrough antennae were not well concentrically aligned and frequency was seen to vary on repeated repositioning of the feedthrough.
  • Simulations need to be performed to see if this effect is reproduced.

Position Cavity

 
  • The BPM was clamped as above and all four ports connected to the VNA.
  • A drop in frequency from 15 MHz was predicted from simulation.
Line: 18 to 25
 
S Parameter S11 S22 S33 S44
Frequency /GHz 14.988 14.991 14.988 14.991
Changed:
<
<

Cross Coupling

>
>

Cross Coupling

  cc.png
Line: 33 to 40
 
META FILEATTACHMENT attachment="short.png" attr="h" comment="" date="1403787681" name="short.png" path="short.png" size="66660" user="ztap061" version="1"
META FILEATTACHMENT attachment="trans.png" attr="h" comment="" date="1403787681" name="trans.png" path="trans.png" size="58687" user="ztap061" version="1"
Changed:
<
<
META FILEATTACHMENT attachment="refl.png" attr="h" comment="" date="1403787681" name="refl.png" path="refl.png" size="67704" user="ztap061" version="1"
>
>
META FILEATTACHMENT attachment="refl.png" attr="h" comment="" date="1403794368" name="refl.png" path="refl.png" size="67704" user="ztap061" version="3"
 
META FILEATTACHMENT attachment="cc.png" attr="h" comment="" date="1403787681" name="cc.png" path="cc.png" size="82812" user="ztap061" version="1"
Added:
>
>
META FILEATTACHMENT attachment="refrefl.png" attr="h" comment="" date="1403794368" name="refrefl.png" path="refrefl.png" size="50987" user="ztap061" version="1"

Revision 126 Jun 2014 - JackTowler

Line: 1 to 1
Added:
>
>
META TOPICPARENT name="NewClicBpm"

RF Tests at RHUL

Reference Cavity

  • The dimensions of the first copper prototype were known to be incorrect. Predicting a frequency drop of ~330 MHz and a loaded Q drop of 160.
  • The BPM was clamped together and the feedthroughs also clamped without the vacuum seals so the separation was increased by 0.45 mm.
  • The VNA was connected to the two ports of the reference cavity where S parameters could be measured.

Position Cavity

  • The BPM was clamped as above and all four ports connected to the VNA.
  • A drop in frequency from 15 MHz was predicted from simulation.

refl.png

S Parameter S11 S22 S33 S44
Frequency /GHz 14.988 14.991 14.988 14.991

Cross Coupling

cc.png

S Parameter S21 S32 S43 S14
Maximum Signal /dB -30.9 -31.0 -39.8 -36.8

-- JackTowler - 26 Jun 2014

short.png

trans.png

META FILEATTACHMENT attachment="short.png" attr="h" comment="" date="1403787681" name="short.png" path="short.png" size="66660" user="ztap061" version="1"
META FILEATTACHMENT attachment="trans.png" attr="h" comment="" date="1403787681" name="trans.png" path="trans.png" size="58687" user="ztap061" version="1"
META FILEATTACHMENT attachment="refl.png" attr="h" comment="" date="1403787681" name="refl.png" path="refl.png" size="67704" user="ztap061" version="1"
META FILEATTACHMENT attachment="cc.png" attr="h" comment="" date="1403787681" name="cc.png" path="cc.png" size="82812" user="ztap061" version="1"
 
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