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The ABP/HSC sectionneeds a 4 port Network Analyzer
for beam impedance measurements
O.Berrig and J.Kuczerowski Thanks to F.Caspers and C.Vollinger
As we all know, a good tool is half the job
HSC = Hadron Synchrotron Collective effects
Beam Impedance measurements are high precision
Network Analyzer
DUT = Device Under Test
The Network Analyzer sends out a sine wave
A linear device i.e. a device without active electronics, always converts an input sine wave to an output sine wave - but with different amplitude and different phase.It is exactly the amplitude and phase change that we want to know !
The Network Analyzer has an extremely narrow band comb filter, which is centered on the same frequency as the one that is sent out
Wire scanner measurementsneeds 4 port Network Analyzer
In general, a differential measurement needs 2 ports. Differential measurements are normally needed for three reasons:1) Engineering constraints (as we have it
in wire scanners)2) Noisy environments3) Long cables
Transverse Beam Impedance measurements can be done easier
with 4 port Network Analyzer
Using 4 ports avoids the non-linearities in the hybrids and makes the measurement less prone to human errors
Automatic measurements requires automatic calibration unit
After an initial measurement of the approximate position of the resonance frequencies; a narrow calibration can be done automatically around each frequency. Each calibration will contain 1601 points (for 1601 frequencies around each resonance frequency).
NB! There are some disagreements if we really need narrow calibrations to find the Q-factors for the resonances. Maybe swept frequency measurements could be used instead?
E5071 Network Analyzers in CERN E5071C VALUCH 864-R-C15 17-11-2011 160072 E5071C VALUCH 864-R-C15 01-03-2011 160003
2838483 E5071C, 9kHz-4.5GHz. 2-port VALUCH 864-R-C15 27.08.2008
4736785 E5071C. 4-port VALUCH 864/R-C15 05.09.20114483087 E5071C. 4-port TRANQUILLE AD 15.10.2010 159950
4130906 E5071C. 2-port TIMEO 17/R-015 25.06.2009 136775
E5071C SCHWERG 252-1-018 09-01-2012 1618514788986 E5071C, 8.5GHz 4-port SCHWERG 252-1-018 04.11.2011
2520524 E5071C. 2-port CHANEL 9-1-021 16-08-2007 125907
4332129 E5071C. 4-port CASPERS 19/S-003 21-04-2010
To be investigated: What about the electronic pool, could we borrow from them?
E5071C M.Wendt BE-BI-QP 866/1-A26
Requirements
Vector Network Analyzer:4 ports.Frequency range: kHz to 3-4 GHzWith Timing optionAutomatic calibration kit needed
Possible vendors:
Keysight – successor of Agilent (selling through retailers – not directly from Keysight)
Rohde & Schwarz
Anritsu
Pro and Cons for purchasing a 4 port network analyzer
Pro:• Time gained because we do not have to
look for someone to lend us a 4 port network analyzer (This only happens for special measurements e.g wire scanner). Also removes the de-motivational effect of having to “beg & borrow”
• Possibility of measuring several ports simultaneously (e.g. measure horizontal and vertical ports simultaneously on a wire scanner)
• With an extra network analyzer, we can do measurements in the lab, while the other network analyzer does automatic measurements in other parts of CERN
• Transverse measurements becomes easier and less error prone.
• Software only need to be written for one network analyzer type. Saves manpower.
Cons:• Price. Approximately 50 kCHF for
network analyzer and automatic calibration kit.
• We have already bought one hybrid (2000+ CHF). This will now only be used rarely e.g. when several differential measurements needs to be done simultaneously. We could sell the Hybrid to the BI group (TID) and borrow it in the rare cases we need it.