evaluation of the te 12 mode in circular waveguides for low-loss high power transportation sami g....
TRANSCRIPT
Evaluation of the TE12 Mode in Circular Waveguides for Low-Loss High Power
Transportation
Sami G. Tantawi, C. Nantista K. Fant, G. Bowden, N. Kroll, and A. VlieksSLAC
Yong Ho Chin, H. Hayano, and Vladimir Vogel KEK
J. NeilsonCalabazas Creek, Inc.
Outline•Introduction•Multi-Moded DLDS•Mode Analyzer•TE12 mode launchers
•TE01 mode launchers•Waveguide Tapers•Transport line measurements• Conclusion
•The high power rf pulse compression techniques suggested for the future linear colliders involves long runs of low loss transportation lines. These runs range from 1000 km to 240 km depending on the system.
•These lines are suppose to carry rf pulses with power levels up to 600 MW for 1.5 micro-seconds at 11.424 GHz. These transportation lines were envisioned to be a circular waveguides with smooth walls using the low loss TE01 mode. Several experimental pulse compression systems based on these lines were built and operated at power levels up to 500 MW[7-8].
•The usage of HE11 mode in corrugated guides were deemed impractical because the corrugation depth required at X-band is large and that made the cost of the waveguide high.
•To reduce the length of the waveguide and consequently the cost, a multi-moded rf system was suggested. The reduction in cost using this technique was analyzed and shown to be considerable.
Delay Lines
Accelerator StructuresBank of nk of klystrons
A set of hybrids that switches the combined rf to different outputs
Not all the output need to be used. The unused outputs are terminated by an rf load
Accelerator Structures
Multi-Moded Delay Lines. The total number of
these lines is np
Bank of klystronskn
A set of hybrids that switches the combined rf to different outputs
A mode launcher which takes nm inputs and produces nm modes into a single waveguide delay line
A Unit of a Single-Moded DLDS
A Unit of a Multi-Moded DLDS
Single-Moded Delay Lines
3 dB 90 Degree Hybrid
Accelerator Structure
Two banks of power sources each has an nk/2 klystrons
3 dB 90 Degree Hybrid
Accelerator Structure
Two banks of power sources each has an nk/2 klystrons
Single-moded Binary Pulse Compression
Single or Multi-Moded Delay Lines
Circulator
Short Circuit
Binary pulse compression can have several improvements including the use of a circulator and several modes to reduce the delay line length.
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1
1.1
1.2
4 6 8 10 12 14 16
Single Moded DLDSMulti-Moded DLDS (number of modes=3)Active DLDSMulti-Moded BPC (A high power circulator and 3 modes)Multi-Moded SLED II (A high power circulator and 3 modes) Active SLED II (One time Switching [7])Multi-Moded DLDS (n
k=4, number of modes =3)
Single-Moded DLDS (nk=4)
Rel
ativ
e C
ost
Compression Ratio
nk=8
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
2 3 4 5 6 7
TE01TE02TE03
TE11TE12TE13
TE21TE22TE31
D
Relative attenuation of different modes per unit time in circular waveguide versus the normalized diameter of the waveguide.
Multi-Moded DLDS System
TE21
TE01 Mode Extractor
TE01 Mode Extractor(Power is Extracted Evenly Between Four Waveguides)
TE01
TE12 (Vertically Polarized)
TE01
TE12 (Vertically Polarized)TE12 (Horizontally Polarized)
Accelerator Structure (~1.8 m)
~7.4 cm Circular Waveguide
TE01
Mode Launcher (Fed by Four Rectangular Waveguides)
Klystrons
~ 6 m
TE12 to TE01 Mode Converter
~53 m
~12.7 cm Circular Waveguide
TE01 Tap-Off TE01 Mode Converter (Fed by Four Rectangular Waveguides)
TE21-TE01 Mode Converter
Circular Guide modes Square Guide ModesTE11 (Polarization #1) TE10TE11(Ploarization #2) TE01TM01 TM11TE21 (Polarization #1) TE20 and TE02 (In Phase)TE21 (Polarization #2) TE11TE01 TE20 and TE02 (out of Phase by 180 degrees)TM11 (Polarization#1) TM12TM11 (Polarization#2) TM21TE31 (Polarization #1) TE12TE31 (Polarization #2) TE21TM21 (Polarization #1) TM22TM21 (Polarization#2) TM13 and TM13 (In phase)TE41 (Polarization#1) TE22TE41 (Polarization#2) TE31 and TE13TE12(Polarization#1) TE30TE12(Polarization#1) TE03TM02 TM31 and TM13 (out of phase by 180 degrees)
Modal Connection Between Circular and Square Waveguides.
(a)
(b)
(a) The Circular-to-Rectangular-Tapers TE12 Mode Transducer. (b) A cut away view of the structure.
Rectangular port (TE10)
Circular Port TE12
This plane is simulated as a perfect magnetic wall
This plane is simulated as a perfect electric wall
Simulated electric field distribution inside the TE12 mode transducer. The colors represent the electric field strength.
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0
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0
11.374 11.399 11.424 11.449 11.474
Data 25
S12
(TE12
-TE10
) S11
S 12 (
TE
12-T
E10
) (d
B)
S11 (dB
)
Frequency (GHz)
Simulated performance of the TE10 (rectangular) to TE12 (circular) mode converter. Simulations are done using HP-HFSS.
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-1
0
-30
-24
-18
-12
-6
0
11.374 11.399 11.424 11.449 11.474
S12
S11
S 12 (
dB) S
11 (dB)
Frequency (GHz)
Measured frequency response of two TE12 mode tranceducers connected back to back.
The Wrap-Around Mode Converter. The physical model shown in the picture does not have the back wall shorting plate, this is done for illustration purposes only.
HFSS simulation results for the wrap around mode converter. The color shades represents the magnitude of the electrical field. (a) is a cut plane through the slots, (b) is a cut plane in the circular guide 2.5 cm away from the slots.
-1
-0.8
-0.6
-0.4
-0.2
0
11.274 11.324 11.374 11.424 11.474 11.524 11.574 11.624
Transmission Coefficient S12 (dB)
dB
Frequency (GHz)
Measured Transmission coefficient for two wrap-around mode converters back to back. The device is optimized at 11.424 GHz.
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.40
0.01
0.02
0.03
0.04
0.05
0.06
TE 12 incident on 2" D
Sum of Reflected power : -30.0 dB
Transmitted power results:Mode OutputPower (dB)----------------------TE 11 -32.7438TM 11 -24.2549TE 12 -0.0187
TE 01 incident on 2" D
Sum of Reflected power : -70 dB
Transmitted power results :Mode OutputPower (dB)----------------------TE 01 -0.0128TE 02 -25.3265TE 03 -49.1235TE 04 -67.0160
Simulation
Arc-taper profile, distances are in meters. Vertical axis is radius and horizontal axis is axial distance
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-2
-1
0
11.399 11.4115 11.424 11.4365 11.449
dB
Freq GHz
Two TE12 mode converters back to back including up tapers to 4.75”
diameter
-5
-4
-3
-2
-1
0
11.399 11.4115 11.424 11.4365 11.449
Freq GHz
dB
Two TE01 mode converters back to back including up tapers to 4.75” diameter
Calculated mode amplitude profiles along the mode rotator, or polarization converter. The asterisks here indicate cross-polarized modes.
MAFIA graphic showing electric field arrows for the WC475 choke resonance. The horizontal axis is r and the vertical axis is z, both in meters. The bottom edge of the plot is the symmetry plane at the gap center.
The Mode Analyzer
Linear Stage
Azimuthal Stage
Outer Pipe (Middle Waveguide)
Inner Pipe (Transport Line Waveguide)
Spring Ring( to guarantee electrical contact)
The orientation of the rectangular waveguide determine the component of the surface magnetic field being measured
The Middle waveguide is connected to the moving stages using a ball joint
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-15
-10
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0
11.374 11.399 11.424 11.449 11.474
TE0 1
TE0 2
TE0 3
TE0 4
dB
Frequency(GHz)
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-35
-30
-25
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-15
-10
-5
0
11.374 11.399 11.424 11.449 11.474
TE1 1TM1 1TE1 2
TM1 2TE1 3TM1 3
TE1 4TM1 4TE1 5
dB
Frequency(GHz)
The scattering of modes due to the step discontinuity when an incident mode is
the TE01 mode
The scattering of modes due to the step discontinuity when an incident mode is
the TE12 mode
HP 8510C Display/Processor
HP 8510C IF Detector
HP 8350 Sweep Oscillator
8514A S-Parameter Test Set
Transport Line, 55 meter of circular waveguide that has a diameter of 12.065 cm diameter
Mode Analyzer
Multi-mode Load
1-Watt Amplifier20-dB Directional Coupler
54 meter of WR90 Rectangular waveguide
All Connections are made with a phase and amplitude stable cables
HP 8510 System Bus
Sweep In
Stop Sweep
Low Noise Amplifier
PC (Pentium based)
GPIB
Mode Launcher
This PC controls both the network analyzer and the mode analyzer. It is also used for data acquisition
Test Set RF Input
Typical Measurement Setup
0
1
2
3
4
5
0
0.02
0.04
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0.08
0.1
0 2 4 6 8 10
Phase (Degrees) Amplitude (dB)
Phas
e (D
egre
es) A
mplitude (dB
)
Time (Hours)
Stability of measurements over time
-9.1
-9.05
-9
-8.95
-8.9
11.349 11.3865 11.424 11.4615 11.499
dB
Freq GHz
Rectangular waveguide calibration measurements
SLAC’s TE12 mode launcher
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0
0 1 2 3 4 5 6
TE0n
ForwardBackward
dB
Radial Wave Number
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-50
-40
-30
-20
-10
0
-180
-120
-60
0
60
120
180
0 1 2 3 4 5 6
TE1n
ForwardBackwardForward Circularly Polarized Wave Angle
dBA
ngle (degrees)
Radial Wave Number
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-40
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-20
-10
0
-180
-120
-60
0
60
120
180
0 1 2 3 4 5 6
TE2n
ForwardBackwardForward Circularly Polarized Wave Angle
dB
Angle (degrees)
Radial Wave Number
-60
-50
-40
-30
-20
-10
0
-180
-120
-60
0
60
120
180
0 1 2 3 4 5 6
TE3n
Forward
Backward
Forward Circularly Polarized Wave Angle
dB
Angle (degrees)
Radial Wave Number
-60
-50
-40
-30
-20
-10
0
-180
-120
-60
0
60
120
180
0 1 2 3 4 5 6
TE5n
ForwardBackwardForward Circularly Polarized Wave Angle
dBA
ngle (degrees)
Radial Wave Number
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-50
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-30
-20
-10
0
-180
-120
-60
0
60
120
180
0 1 2 3 4 5 6
TE4n
ForwardBackwardForward Circularly Polarized Wave Angle
dB
Angle (degrees)
Radial Wave Number
-60
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-20
-10
0
0 1 2 3 4 5 6
TE0n
ForwardBackward
dB
Radial Wave Number
-60
-50
-40
-30
-20
-10
0
-180
-120
-60
0
60
120
180
0 1 2 3 4 5 6
TE1n
ForwardBackwardForward Circularly Polarized Wave Angle
dB
Angle (degrees)
Radial Wave Number
-60
-50
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-30
-20
-10
0
-180
-120
-60
0
60
120
180
0 1 2 3 4 5 6
TE2n
ForwardBackwardForward Circularly Polarized Wave Angle
dB
Angle (degrees)
Radial Wave Number
-60
-50
-40
-30
-20
-10
0
-180
-120
-60
0
60
120
180
0 1 2 3 4 5 6
TE3n
ForwardBackwardForward Circularly Polarized Wave Angle
dB
Angle (degrees)
Radial Wave Number
-60
-50
-40
-30
-20
-10
0
-180
-120
-60
0
60
120
180
0 1 2 3 4 5 6
TE4n
ForwardBackwardForward Circularly Polarized Wave Angle
dB
Angle (degrees)
Radial Wave Number
-60
-50
-40
-30
-20
-10
0
-180
-120
-60
0
60
120
180
0 1 2 3 4 5 6
TE5n
ForwardBackwardForward Circularly Polarized Wave Angle
dB
Angle (degrees)
Radial Wave Number
Measured Mode spectrum of the TE01 mode transducer.
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-10
0
0 1 2 3 4 5 6
TE1n (KEK)
ForwardBackward
dB
Radial Wave Number
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-20
-10
0
0 1 2 3 4 5
TE0n
ForwardBackward
dB
Radial Wave Number
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-20
-10
0
0 1 2 3 4 5
TE2n
ForwardBackward
dB
Radial Wave Number
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-10
0
0 1 2 3 4 5
TE3n
ForwardBackward
dB
Radial Wave Number
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-10
0
0 1 2 3 4 5
TE4n
ForwardBackward
dB
Radial Wave Number
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0
0 1 2 3 4 5
TE5n
ForwardBackward
dBRadial Wave Number
Mode Spectrum of the KEK Mode Launcher
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0
0.5 1 1.5 2 2.5 3 3.5 4 4.5
TE0n
ForwardBackward
dB
Radial Wave Number
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-10
0
0 1 2 3 4 5 6
TE1n
ForwardBackward
dBRadial Wave Number
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-10
0
0 1 2 3 4 5
TE2n
ForwardBackward
dB
Radial Wave Number
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-20
-10
0
0 1 2 3 4 5
TE3n
ForwardBackward
dB
Radial Wave Number
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-20
-10
0
0.5 1 1.5 2 2.5 3 3.5
TE4n
ForwardBackward
dB
Radial Wave Number
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-10
0
0.5 1 1.5 2 2.5 3 3.5
TE5n
ForwardBackward
dBRadial Wave Number
U of Maryland
Mode Spectrum after the 55 meter of Waveguide.The mode is Launched using SLAC’s TE12 mode converter
-60
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-10
0
0 1 2 3 4 5 6
TE0n
ForwardBackward
dB
Radial Wave Number
-60
-50
-40
-30
-20
-10
0
-180
-120
-60
0
60
120
180
0 1 2 3 4 5 6
TE1n
ForwardBackwardForward Circularly Polarized Wave Angle
dB
Angle (degrees)
Radial Wave Number
-60
-50
-40
-30
-20
-10
0
-180
-120
-60
0
60
120
180
0 1 2 3 4 5 6
TE2n
ForwardBackwardForward Circularly Polarized Wave Angle
dB
Angle (degrees)
Radial Wave Number
-60
-50
-40
-30
-20
-10
0
-180
-120
-60
0
60
120
180
0 1 2 3 4 5 6
TE3n
ForwardBackwardForward Circularly Polarized Wave Angle
dB
Angle (degrees)
Radial Wave Number
-60
-50
-40
-30
-20
-10
0
-180
-120
-60
0
60
120
180
0 1 2 3 4 5 6
TE4n
ForwardBackwardForward Circularly Polarized Wave Angle
dB
Angle (degrees)
Radial Wave Number
-60
-50
-40
-30
-20
-10
0
-180
-120
-60
0
60
120
180
0 1 2 3 4 5 6
TE5n
ForwardBackwardForward Circularly Polarized Wave Angle
dB
Angle (degrees)
Radial Wave Number
-60
-50
-40
-30
-20
-10
0
0 1 2 3 4 5 6
TE0n
ForwardBackward
dB
Radial Wave Number
-60
-50
-40
-30
-20
-10
0
-180
-120
-60
0
60
120
180
0 1 2 3 4 5 6
TE1n
ForwardBackwardForward Circularly Polarized Wave Angle
dB
Angle (degrees)
Radial Wave Number
-60
-50
-40
-30
-20
-10
0
-180
-120
-60
0
60
120
180
0 1 2 3 4 5 6
TE2n
ForwardBackwardForward Circularly Polarized Wave Angle
dB
Angle (degrees)
Radial Wave Number
-60
-50
-40
-30
-20
-10
0
-180
-120
-60
0
60
120
180
0 1 2 3 4 5 6
TE3n
ForwardBackwardForward Circularly Polarized Wave Angle
dB
Angle (degrees)
Radial Wave Number
-60
-50
-40
-30
-20
-10
0
-180
-120
-60
0
60
120
180
0 1 2 3 4 5 6
TE4n
ForwardBackwardForward Circularly Polarized Wave Angle
dB
Angle (degrees)
Radial Wave Number
-60
-50
-40
-30
-20
-10
0
-180
-120
-60
0
60
120
180
0 1 2 3 4 5 6
TE5n
ForwardBackwardForward Circularly Polarized Wave Angle
dB
Angle (degrees)
Radial Wave Number
Mode Spectrum after the 55 meter of Waveguide.The mode is Launched using SLAC’s TE01 mode converter
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-1
0
11.399 11.4115 11.424 11.4365 11.449
dB
Frequency (GHz)
0
0.2
0.4
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0.8
1
7.5 8 8.5 9 9.5
Horizontal
OutputInput
Out
put
Time(micro-seconds)
Transmission Measurement through a TE12 mode launcher 55-meter of WC475 Waveguide and a receiving TE12 Mode
Converter. The TE12 was Launched and received with horizontal polarization
0
0.2
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1
7.5 8 8.5 9 9.5
timedomaindata
Horizontal AlignedVertical AlignedReceiver and Transmitter aligned 45 degrees
with respect to the vertical direction Input
Time(micro-seconds)
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0
11.399 11.4115 11.424 11.4365 11.449
dB
Frequency (GHz)
Time domain response of the transport line plus the mode launchers (two mode transducers plus two arc-tapers). In this figure the two mode transducers were always aligned with respect to each other
0.9
0.92
0.94
0.96
0.98
1
7.8 8 8.2 8.4 8.6
Input
Receiver aligned 10 degrees off transmitter
Horizontal AlignedReceiver aligned 4 degrees off transmitter
Rel
ativ
e A
mpl
itude
Time(micro-seconds)
The effect of rotating one of the mode TE12 mode transducer with respect to the other.
-5
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-1
0
11.399 11.4115 11.424 11.4365 11.449
dB
Freq GHz
0
0.2
0.4
0.6
0.8
1
7.5 8 8.5 9 9.5
Input Output
Rel
ativ
e A
mpl
itude
Time(micro-seconds)
Time domain response of the transport line plus the mode launchers (two TE01 mode transducers plus two arc-tapers).
•Losses Of The TE01 Mode is 1.08%; Theory is 1.1%•Losses of the TE12 Mode is 4.5% to 5.1% (Polarization dependant);Theory is 2.8%•No mode rotation was observed•None of the mode TE12 converters performed satisfactory.
Conclusion•We have demonstrated the possibility of using the TE12 mode in highly over-moded circular waveguides as a means of low-loss transport of rf signals. The over all losses were small and compared relatively well with theory.
•The waveguide used in the experiments were extruded oxygen-free high-conductivity copper. It was shown that these waveguides could be manufactured good enough to eliminate all cross polarization mode mixing. Nonetheless, we observed some conversion to the virtually degenerate mode, TE41. However, the conversion levels were small.
•We also compared our results for TE12 with those of the low loss TE01. In this process we showed that connecting flanges and waveguides could be used to propagate either modes. This paves the way to developing a multi-moded system were different signals could be loaded over different modes.
• We reported a novel technique for measuring the modal content of a highly over-moded waveguides. We also, reported a technique for efficiently exiting the TE12 mode and the TE01 mode. Finally, we showed how to design and implement a polarization
rotator for the TE12 mode.
•Over the 55 meter of WC475 losses of The TE01 Mode is 1.08%; Theory is 1.1%.
Losses of the TE12 Mode is 4.5% to 5.1%; theory is 2.8%
The Mode analyzer being Aligned
The Mode Analyzer System
TE12 Mode Launcher, a spacer for the mode rotator, nonlinear taper and, transport line
The end of the mode analyzer and transport line is terminated by a multi-moded load
The Wrap-Around Mode Converter, The Arc-Taper, and the Mode Analyzer