Transcript Evaluation of the TE Mode in Circular Waveguides for Low-Loss High Power Transportation

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.
Vlieks
SLAC
Yong Ho Chin, H. Hayano, and Vladimir Vogel
KEK
J. Neilson
Calabazas 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 Structures
Bank of nk of klystrons
Not all the output need to be used. The
unused outputs are terminated by an rf
load
A set of hybrids that switches the combined
rf to different outputs
A Unit of a Single-Moded DLDS
Multi-Moded Delay
Lines. The total number
of these lines is np
A mode launcher which takes nm inputs
and produces nm modes into a single
waveguide delay line
Accelerator Structures
Bank nkof klystrons
A set of hybrids that switches the combined
rf to different outputs
A Unit of a Multi-Moded DLDS
Two banks of power sources each has an nk/2 klystrons
3 dB 90 Degree Hybrid
Single-Moded Delay
Lines
Accelerator Structure
Single-moded Binary Pulse Compression
Two banks of power sources each has an nk/2 klystrons
3 dB 90 Degree Hybrid
Short Circuit
Single or Multi-Moded
Delay Lines
Circulator
Accelerator Structure
Binary pulse compression can have several
improvements including the use of a circulator and
several modes to reduce the delay line length.
Single Moded DLDS
Multi-Moded DLDS (number of modes=3)
Active DLDS
Multi-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 =4, number of modes =3)
n =8
k
k
Single-Moded DLDS (n =4)
k
1.2
Relative Cost
1.1
1
0.9
0.8
0.7
0.6
0.5
4
6
8
10
12
Compression Ratio
14
16
TE01
TE02
TE03
TE11
TE12
TE13
TE21
TE22
TE31
0.4
0.35
0.3

0.25
0.2
0.15
0.1
0.05
0
2
3
4
5
6
7
D
Relative attenuation of different modes per unit time in circular
waveguide versus the normalized diameter of the waveguide.
TE01
TE12 (Vertically Polarized)
TE12 (Horizontally Polarized)
~12.7 cm Circular Waveguide
TE01
TE12 (Vertically Polarized)
TE01 Mode
Extractor
Klystrons
~7.4 cm Circular Waveguide
TE01 Mode Extractor
(Power is Extracted Evenly Between
Four Waveguides)
TE01
Accelerator Structure (~1.8 m)
TE21
TE01 Tap-Off
TE12 to TE01
Mode Converter
Mode Launcher (Fed
by Four Rectangular
Waveguides)
TE01 Mode Converter
(Fed by Four
Rectangular
Waveguides)
~6m
TE21-TE01 Mode Converter
~53 m
Multi-Moded DLDS System
Circular Guide modes
TE11 (Polarization #1)
TE11(Ploarization #2)
TM01 TM11
TE21 (Polarization #1)
TE21 (Polarization #2)
TE01
TM11 (Polarization#1)
TM11 (Polarization#2)
TE31 (Polarization #1)
TE31 (Polarization #2)
TM21 (Polarization #1)
TM21 (Polarization#2)
TE41 (Polarization#1)
TE41 (Polarization#2)
TE12(Polarization#1)
TE12(Polarization#1)
TM02
Square Guide Modes
TE10
TE01
TE20 and TE02 (In Phase)
TE11
TE20 and TE02 (out of Phase by 180 degrees)
TM12
TM21
TE12
TE21
TM22
TM13 and TM13 (In phase)
TE22
TE31 and TE13
TE30
TE03
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)
This plane is simulated
as a perfect electric wall
Circular Port TE12
This plane is simulated as a
perfect magnetic wall
Simulated electric field distribution inside the TE12 mode transducer.
The colors represent the electric field strength.
S (TE -TE )
12
12
S
10
11
-6
-0.2
-12
-0.3
-18
-0.4
-24
12
12
10
-0.1
11
0
S (dB)
S (TE -TE ) (dB)
Data 25
0
-0.5
11.374
11.399
11.424
11.449
-30
11.474
Frequency (GHz)
Simulated performance of the TE10 (rectangular) to TE12 (circular)
mode converter. Simulations are done using HP-HFSS.
S
S
11
0
-1
-6
-2
-12
-3
-18
-4
-24
12
11
0
S (dB)
S (dB)
12
-5
11.374
11.399
11.424
11.449
-30
11.474
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.
Transmission Coefficient S12 (dB)
0
-0.2
dB
-0.4
-0.6
-0.8
-1
11.274
11.324
11.374
11.424
11.474
11.524
11.574
11.624
Frequency (GHz)
Measured Transmission coefficient for
two wrap-around mode converters
back to back. The device is optimized
at 11.424 GHz.
TE 12 incident on 2" D
Sum of Reflected power : -30.0 dB
Transmitted power results:
Mode Output
Power (dB)
---------------------TE 11 -32.7438
TM 11 -24.2549
TE 12 -0.0187
TE 01 incident on 2" D
Sum of Reflected power : -70 dB
Transmitted power results :
Mode Output
Power (dB)
---------------------TE 01 -0.0128
TE 02 -25.3265
TE 03 -49.1235
TE 04 -67.0160
Simulation
0.06
0.05
0.04
0.03
0.02
0.01
0
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
Arc-taper profile, distances are in meters.
Vertical axis is radius and horizontal axis is
axial distance
0
-1
dB
-2
-3
-4
-5
11.399
11.4115
11.424
11.4365
11.449
Freq GHz
Two TE12 mode converters back to
back including up tapers to 4.75”
diameter
0
-1
dB
-2
-3
-4
-5
11.399
11.4115
11.424
Freq GHz
11.4365
11.449
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-polariz
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.
Azimuthal Stage
Linear Stage
Outer Pipe
(Middle Waveguide)
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
Inner Pipe
(Transport Line Waveguide)
Spring Ring
( to guarantee electrical contact)
The Mode Analyzer
T E0 3
T E0 2
T E0 4
T E1 1
T M1 1
T E1 2
0
0
-5
-5
-10
-10
-15
-15
-20
-20
dB
dB
T E0 1
-25
-25
-30
-30
-35
-35
-40
11.374
11.399
11.424
11.449
11.474
Frequency(GHz)
The scattering of modes due to the step
discontinuity when an incident mode is
the TE01 mode
-40
11.374
T M1 2
T E1 3
T M1 3
11.399
11.424
T E1 4
T M1 4
T E1 5
11.449
11.474
Frequency(GHz)
The scattering of modes due to the step
discontinuity when an incident mode is
the TE12 mode
Mode Launcher
Transport Line, 55 meter of circular
waveguide that has a diameter of 12.065 cm
diameter
Mode Analyzer
Multi-mode Load
Low Noise
Amplifier
54 meter of WR90 Rectangular waveguide
HP 8510C
Display/Processor
All Connections are made with a phase
and amplitude stable cables
HP 8510C IF
Detector
HP 8510
System Bus
Sweep In
Stop Sweep
8514A S-Parameter
Test Set
Test Set RF Input
HP 8350 Sweep
Oscillator
20-dB Directional Coupler
1-Watt Amplifier
This PC controls both the network analyzer and
the mode analyzer. It is also used for data
acquisition
Typical Measurement Setup
GPIB
PC (Pentium
based)
Amplitude (dB)
5
0.1
4
0.08
3
0.06
2
0.04
1
0.02
0
0
0
2
4
6
Time (Hours)
8
Amplitude (dB)
Phase (Degrees)
Phase (Degrees)
10
Stability of measurements over time
-8.9
dB
-8.95
-9
-9.05
-9.1
11.349
11.3865
11.424
11.4615
11.499
Freq GHz
Rectangular waveguide calibration measurements
SLAC’s TE12 mode launcher
Forward
Backward
Forward Circularly Polarized Wave
Forward
Backward
0
180
-10
-10
120
-10
120
-20
-20
60
-20
60
-30
0
-30
0
-40
-40
-60
-40
-60
-50
-50
-120
-50
-120
-180
-60
-30
-60
0
1
2
3
4
5
6
0
1
Radial Wave Number
2
3
4
5
dB
180
dB
0
6
-180
0
1
Radial Wave Number
Forward
Backward
Forward Circularly Polarized Wave
TE3n
2
3
4
5
6
Radial Wave Number
Forward
Backward
Forward Circularly Polarized Wave
Angle
Forward
Backward
Forward Circularly Polarized Wave
Angle
TE5n
Angle
TE4n
180
-10
120
-10
120
-10
120
-20
60
-20
60
-20
60
-30
0
-30
0
-30
0
-40
-60
-40
-60
-40
-60
-50
-120
-50
-120
-50
-120
-180
-60
-180
-60
0
1
2
3
4
Radial Wave Number
5
6
0
1
2
3
4
Radial Wave Number
5
6
dB
0
dB
180
-180
0
1
2
3
4
Radial Wave Number
5
6
Angle (degrees)
0
Angle (degrees)
180
Angle (degrees)
0
-60
Angle (degrees)
0
-60
dB
Angle
TE2n
TE1n
Angle (degrees)
dB
TE0n
Forward
Backward
Forward Circularly Polarized Wave
Angle
Measured Mode spectrum of the TE01 mode transducer.
Forward
Backward
Forward Circularly Polarized Wave
TE1n
Forward
Backward
180
-10
-10
120
-10
120
-20
-20
60
-20
60
-30
0
-30
0
-40
-40
-60
-40
-60
-50
-50
-120
-50
-120
-180
-60
-30
-60
0
1
2
3
4
5
6
0
1
2
3
4
5
dB
0
dB
180
6
-180
0
1
2
3
4
Radial Wave Number
Radial Wave Number
Radial Wave Number
Forward
Backward
Forward Circularly Polarized Wave
Forward
Backward
Forward Circularly Polarized Wave
TE4n
Forward
Backward
Forward Circularly Polarized Wave
TE5n
Angle
TE3n
Angle
5
6
Angle
180
-10
120
-10
120
-10
120
-20
60
-20
60
-20
60
-30
0
-30
0
-30
0
-40
-60
-40
-60
-40
-60
-50
-120
-50
-120
-50
-120
-180
-60
-180
-60
0
1
2
3
4
Radial Wave Number
5
6
0
1
2
3
4
Radial Wave Number
5
6
dB
0
dB
180
-180
0
1
2
3
4
Radial Wave Number
5
6
Angle (degrees)
0
Angle (degrees)
180
Angle (degrees)
0
-60
Angle (degrees)
0
-60
dB
Angle
0
Angle (degrees)
dB
TE0n
Forward
Backward
Forward Circularly Polarized Wave
TE2n
Angle
Mode Spectrum of the KEK Mode Launcher
Forward
Backward
Forward
Backward
Forward
Backward
TE1n (KEK)
-10
-10
-10
-20
-20
-20
-30
dB
0
-30
-30
-40
-40
-40
-50
-50
-50
-60
-60
0
1
2
3
4
5
-60
0
1
2
Radial Wave Number
3
4
5
6
0
TE4n
-10
-10
-20
-20
-20
dB
-10
dB
0
-30
-40
-40
-50
-50
-50
-60
5
5
-30
-40
2
3
4
Radial Wave Number
4
TE5n
0
-30
3
Forward
Backward
TE3n
1
2
Radial Wave Number
Forward
Backward
0
-60
0
1
Radial Wave Number
Forward
Backward
dB
TE2n
0
dB
dB
TE0n
0
-60
0
1
2
3
Radial Wave Number
4
5
0
1
2
3
Radial Wave Number
4
5
U of Maryland
Forward
Backward
Forward
Backward
Forward
Backward
TE1n
-10
-10
-10
-20
-20
-20
-30
dB
0
-30
-30
-40
-40
-40
-50
-50
-50
-60
0.5
-60
1
1.5
2
2.5
3
3.5
4
4.5
-60
0
1
Radial Wave Number
2
3
4
5
6
0
Forward
Backward
TE4n
-10
-10
-20
-20
-20
dB
-10
dB
0
-30
-40
-40
-50
-50
-50
2
3
Radial Wave Number
4
5
-60
0.5
1
5
-30
-40
-60
4
TE5n
0
-30
3
Forward
Backward
TE3n
1
2
Radial Wave Number
0
0
1
Radial Wave Number
Forward
Backward
dB
TE2n
0
dB
dB
TE0n
0
1.5
2
2.5
Radial Wave Number
3
3.5
-60
0.5
1
1.5
2
2.5
Radial Wave Number
3
3.5
Mode Spectrum after the 55 meter of Waveguide.
The mode is Launched using SLAC’s TE12 mode converter
Forward
Backward
Forward Circularly Polarized Wave
TE1n
0
Forward
Backward
TE0n
Angle
TE2n
180
0
180
-10
120
-20
-20
60
-20
60
-30
0
-30
0
-40
-40
-60
-40
-60
-50
-50
-120
-50
-120
-180
-60
-30
-60
0
1
2
3
4
5
6
0
1
Radial Wave Number
2
3
4
5
dB
120
dB
-10
6
-180
0
1
Radial Wave Number
Forward
Backward
Forward Circularly Polarized Wave
Angle
2
3
4
5
6
Radial Wave Number
Forward
Backward
Forward Circularly Polarized Wave
TE3n
Forward
Backward
Forward Circularly Polarized Wave
Angle
TE4n
Angle
TE5n
180
-10
120
-10
120
-10
120
-20
60
-20
60
-20
60
-30
0
-30
0
-30
0
-40
-60
-40
-60
-40
-60
-50
-120
-50
-120
-50
-120
-180
-60
-180
-60
0
1
2
3
4
Radial Wave Number
5
6
0
1
2
3
4
Radial Wave Number
5
6
dB
0
dB
180
-180
0
1
2
3
4
Radial Wave Number
5
6
Angle (degrees)
0
Angle (degrees)
180
Angle (degrees)
0
-60
Angle (degrees)
-10
-60
dB
Angle
Angle (degrees)
dB
0
Forward
Backward
Forward Circularly Polarized Wave
Mode Spectrum after the 55 meter of Waveguide.
The mode is Launched using SLAC’s TE01 mode converter
Forward
Backward
Forward Circularly Polarized Wave
Forward
Backward
TE1n
0
180
-10
-10
120
-10
120
-20
-20
60
-20
60
-30
0
-30
0
-40
-40
-60
-40
-60
-50
-50
-120
-50
-120
-180
-60
-30
-60
0
1
2
3
4
5
6
0
1
Radial Wave Number
2
3
4
5
dB
180
dB
0
6
-180
0
1
Radial Wave Number
Forward
Backward
Forward Circularly Polarized Wave
TE3n
2
3
4
5
6
Radial Wave Number
Forward
Backward
Forward Circularly Polarized Wave
TE4n
Angle
Forward
Backward
Forward Circularly Polarized Wave
TE5n
Angle
Angle
180
-10
120
-10
120
-10
120
-20
60
-20
60
-20
60
-30
0
-30
0
-30
0
-40
-60
-40
-60
-40
-60
-50
-120
-50
-120
-50
-120
-180
-60
-180
-60
0
1
2
3
4
Radial Wave Number
5
6
0
1
2
3
4
Radial Wave Number
5
6
dB
0
dB
180
-180
0
1
2
3
4
Radial Wave Number
5
6
Angle (degrees)
0
Angle (degrees)
180
Angle (degrees)
0
-60
Angle (degrees)
0
-60
dB
Angle
TE2n
Angle (degrees)
dB
TE0n
Forward
Backward
Forward Circularly Polarized Wave
Angle
Output
Input
Horizontal
0
1
-1
0.8
dB
Output
-2
-3
0.4
-4
-5
11.399
0.6
0.2
11.4115
11.424
Frequency (GHz)
11.4365
11.449
0
7.5
8
8.5
9
Time(micro-seconds)
9.5
Transmission Measurement through a TE12 mode launcher 55meter of WC475 Waveguide and a receiving TE12 Mode
Converter. The TE12 was Launched and received with
horizontal polarization
Horizontal Aligned
Vertical Aligned
Receiver and Transmitter aligned 45 degrees
with respect to the vertical direction
timedomaindata
Input
0
1
-1
0.8
-2
dB
0.6
-3
0.4
-4
0.2
-5
11.399
11.4115
11.424
Frequency (GHz)
11.4365
11.449
0
7.5
8
8.5
9
9.5
Time(micro-seconds)
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
Input
Horizontal Aligned
Receiver aligned 4 degrees off transmitter
Receiver aligned 10 degrees off transmitter
1
Relative Amplitude
0.98
0.96
0.94
0.92
0.9
7.8
8
8.2
8.4
Time(micro-seconds)
8.6
The effect of rotating one of the mode TE12 mode transducer with
respect to the other.
Input
Output
0
1
Relative Amplitude
-1
dB
-2
-3
-4
-5
11.399
0.8
0.6
0.4
0.2
11.4115
11.424
Freq GHz
11.4365
11.449
0
7.5
8
8.5
9
9.5
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 overmoded 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