WFM electronics
Alexandra Andersson
WFM experiment in CLEX
 Wakefield Monitors implemented in two accelerating structures TD24 (tank
version, without SiC loads (except for the WFM))
 Each WFM will study two different modes:
 TM like mode at ~ 18 GHz (+ hybrid recombination)
 TE like mode at ~ 24 GHz
 RF Design finished (GdfidL + HFSS simulations)
 Mechanical design under progress (CERN)
 Connectors, Vacuum cables, 3dB/180° Hybrids ordered
Port signals for beam offset ∆x=1mm
Waveguide bend
TM (+ perfect hybrid)
SiC load
18 GHz
TM modes
TE modes
F. Peauger – CTF3 committee – 11/02/10
TE
24 GHz
2
Fabrication of the accelerating structures
 Qualification of three firms for precise machining (2 prototypes)
 Results of Firm n°1:
• Very low roughness of turned surfaces Ra =
0.009 to 0.022 (spec=0.025)
• Roughness of milled faces higher (factor of 10)
but can be improved with monocristal cutting tool
• Tolerances within 3 µm (spec=2.5)
• Planarity of 1.7 – 3.2 µm (spec=2µm), can be
improved by better stress relieve process
 Very promising results
 Results from Firms n°2 and 3 expected in few weeks
 Schedule (target):
- all the disks for the two structures machined:
- structures ready for test with beam on TBTS:
 But challenging planning
mid 2010
end 2010 ?
 Note: need maybe an additional BPM on TBTS, just before the structure (to be
discussed)
F. Peauger – CTF3 committee – 11/02/10
3
Detection scheme
•
•
•
•
•
•
•
•
•
Waveguide
Waveguide to coax
Power limiter
Low Noise Amplifier
Down mix with 18GHz (24->6, 22.5->4.5, ...)
Power splitter
Magnitude detected with logarithmic diode detector
BandPass around 6GHz for phase detection
Compare to phase of the 12GHz RF. Use Local Oscillator
of common derivation
Detection Scheme
From
WFM 23G
(18G, 12G)
LNA
18G
(12G, 6G)
o
6G
90
6G
LO generation
6GHz
×2
×3
×2
18GHz
VCO, 3G
÷32
÷2
Divide by N PLL
16.384M 17M
64.384M
187.384M
48M 55M
75M
78M
123M
Noise
Loss/Gain
Noise, F
Gain casc.
Noise Casc. Noise Casc. Gain casc.
Component
[dB]
Noise Figure Gain linear (linear)
(linear)
(linear)
dB/Hz
dB
damped waveguide
-10.0
10.0
0.1
10.0
0.1
10.0
10.0
-10.0
vacuum cable
-2.0
2.0
0.6
1.6
0.1
15.8
12.0
-12.0
vacuum feedthrough
-0.5
0.5
0.9
1.1
0.1
17.8
12.5
-12.5
Waveguide -> sma
transition
Waveguide and
flanges
Waveguide -> sma
transition
PIN diode limiter
Low Noise Amplifier
Mixer
Power Splitter
0.0
0.0
1.0
1.0
0.1
17.9
12.5
-12.5
-3.7
3.7
0.4
2.3
0.0
42.0
16.2
-16.2
0.0
-2.5
-18.8
30.0
-7.0
-5.0
0.0
2.5
1.0
0.6
1.0
1.8
0.0
0.0
42.4
75.4
16.3
18.8
-16.3
-18.8
2.5
7.0
5.0
1000.0
0.2
0.3
1.8
5.0
3.2
13.3
2.6
0.8
134.0
134.3
135.2
21.3
21.3
21.3
11.2
4.2
-0.8
dBm/Hz (-174dBm/Hz + Casc. Noise Figure)
mW/Hz
mW
dBm
-152.7
5.4E-16
1.1E-06
W
-59.7
1.1E-09
Frequencies and phases
Frequency
Phase
LO 1 (crystal oscillator)
16.384 MHz
φ1
LO 2 (crystal oscillator)
48 MHz
φ2
LO 3 (crystal oscillator)
75 MHz
φ3
Mixer 1, LO1xLO2
64.384 MHz
φ1+φ2
Mixer 2, LO2xLO3
123 MHz
φ2+φ3
Mixer 3, Mix1xMix2
187.384 MHz
φ1+2φ2+φ3
LO = Mix 3 x16 (divide-by-N PLLL)
2998.144 MHz
φLO=16(φ1+2φ2+φ3)
2xLO (frequency doubler)
5996.288 MHz
2φLO
6xLO (frequency tripler, doubler)
17988.864 MHz
6φLO
WFM signal
23988.4 MHz
φWFM
DownMix1 = WFM x (6xLO)
5999.536 MHz
φWFM -6φLO
IQ1=DownMix1x(2xLO)
3.248 MHz
φWFM -8φLO
RF signal
11994.2 MHz
φRF
DownMix2 = RF x (2xLO)
5997.912 MHz
φRF -2φLO
IQ2=DownMix2x(2xLO)
1.624 MHz
φRF -4φLO
Phase WFM-RF = IQ1-2IQ2
φWFM -2φRF
Waveguide
194mm
Waveguide
534mm
Waveguide