Post on 26-Jan-2021
By Germán Cortés M.
Antenna Optical Design and Wide Band Feed Development
for the SKA TDP
Cornell UniversityCornell UniversityIthaca NY 14853, USA
National Astronomy and Ionosphere Center
Cornell UniversityCornell UniversityIthaca NY 14853, USA
Acknowledgements
National Astronomy and Ionosphere Center
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Overview
• US SKA Technology Development Project (SKA TDP)• SKA Technology Paths: Dishes + WBSPF• The TDP Wide Band Feed Development: QSC Feed• SKA TDP Optics Design• Summary and Concluding Remarks
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rThe US-SKA Technology Development Project (TDP)
US SKA Technology Development Project– NSF-funded 2007-2011 for $12M– Complementary to and integrated with PrepSKA– Targets areas that bear strongly on cost and basic performance
(Ae, Tsys, B, cross polarization, processing) – Will deliver to the SKA project:
• Technology options for LNSD array with single-pixel feeds• Costing of reflectors+mounts vs. D and fmax• Optical designs that include both WBSP + PAF options• An SKA optimized, fully outfitted antenna• Calibration and processing algorithms for LNSD arrays• Cost-modeling information
US Technology Development Project for the SKA, Jim CordesAWG Meeting , 13-14 March 2008, San Francisco, USAhttp://skatdp.astro.cornell.edu/
US Technology Development Project for the SKA, Jim CordesAWG Meeting , 13-14 March 2008, San Francisco, USAhttp://skatdp.astro.cornell.edu/
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rThe US-SKATechnology Development Project (TDP)
Work Breakdown Structure for the TDP1. Antennas, Feeds and Receivers2. Calibration and Processing3. Cost Function Analysis4. Interface to International SKA Design Project
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rThe US-SKATechnology Development Project (TDP)
Cost Function Analysis
Parabolic Dishes,David DeBoer, France, Sep 2006Parabolic Dishes,David DeBoer, France, Sep 2006
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rThe US-SKATechnology Development Project (TDP)
The Timeline
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SKA Technology Path Implementation:Dishes + Wide Band Single Pixel Feeds
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rInternational SKATechnology Path Implementation
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rInternational SKATechnology Path Implementation
Frequency
2a
2bPH
AS
E I 1
PAF’sAA’s
0.07 0.2 0.5 0.8 1.5 10 GHzAA’s
1.5 GHz 10 GHz
0.5 GHz 10 GHz 65%
65%
ηA
35K
35K
Tsys
Dishes + WBSPF
Dishes Ø15m + WBSPF
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rInternational SKATechnology Path Implementation
70%
70%
70%
ηA
30K
30K
30K
Tsys
Frequency
3cPH
AS
E I
I
AA’s
AA’s
1.5 GHz 10 GHz
0.8 GHz 10 GHz
0.5 GHz 10 GHz3a
3b
1
2
0.07 0.2 0.5 0.8 1.5 10 GHzDishes Ø15m + WBSPF
AA’s
PAF’s
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Dishes + WBSPF
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rUS SKA TDPTop Level Specs for Dishes + WBSP Feeds
70%
70%
70%
ηA
30K
30K
30K
Tsys
Frequency
1.5 GHz 10 GHz
0.8 GHz 10 GHz
0.5 GHz 10 GHz
0.07 0.2 0.5 0.8 1.5 10 GHzDishes Ø15m + WBSPF
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rUS SKA TDPTop Level Specs for Dishes + WBSP Feeds
70%
70%
70%
ηA
30K
30K
30K
Tsys
Frequency
1.5 GHz 10 GHz
0.8 GHz 10 GHz
0.5 GHz 10 GHz
0.07 0.2 0.5 0.8 1.5 10 GHz
1.0 GHz 10 GHz
0.3 3 GHz
TDP
Fee
ds
Room Temp
Cooled
30K
Dishes Ø15m + WBSPF
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SKA TDP Wide Band Feed Development:The QSC Feed
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rUS SKA TDPThe TDP WBSP Feeds
www.seti.org
•Allen Telescope Array or ATA
•Frequency: 0.5 to 11.5 GHz
•The -10dB HBW=43°
•Phase Center is frequency dependent•Size: 0.3 m x 0.3 m x 1.2 m
•Good Match, better than –14 dB
The ATA Feed
Non-planar log-periodic antenna feed for integration with a cryogenic microwave amplifier, G. EngargiolaAntennas and Propagation Society International Symposium 2002, IEEE San Antonio, TX, Volume 4, 16-21 June 2002 Page(s):140 - 143 vol.4
Tn ~40 to 45K over 7:1 BW
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rUS SKA TDPThe TDP WBSP Feeds
The eleven antenna: a compact low-profile decade bandwidth dual polarized feed for reflector antennas. R. Olson, P.S. Kildal, and S. Weinreb. IEEE Transactions on Ant and Prop, vol 54, no 2, part 1, Feb 2006, pp. 368–375.
The Chalmers Feed or “Eleven” Feed
•Frequency: 11:1 Bandwidth
•The -10dB HBW ~ 62°
•Phase Center is frequency independent
•Compact Size (0.65 λmax)2 x 0.21 λmax•Input Matching better than –8 (-10?) dB
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rUS SKA TDPThe TDP WBSP Feeds
•Frequency: 8:1 Bandwidth
•The -10dB HBW is frequency dependent
•Phase Center varies with frequency
•Size ~(1.1 λmax)2 x 1.2 λmax•Input Matching better than –6 dB
Feed Based on the Quad-Ridge Lindgren Horn
Design of a Wideband Radio Telescope, William A. Imbriale, Sander Weinreb and Handi Mani.IEEE 2007 Aerospace Conference, Big Sky, Montana, March, 2007
S. Weinreb, Caltech
Frequency: 4 to 12 GHzTn ~30K
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rUS SKA TDPThe TDP WBSP Feeds
•Frequency: 10:1 Bandwidth
•The -10dB HBW is ~ 65°
•Phase Center is frequency independent
•Size ~(?λmax)2 x ? λmax•Input Matching better than –8? dB
Inverted, Conical, Sinuous Antenna over a Ground Plane
The Inverted, Conical, Sinuous Antenna over a Ground Plane, Rohit S. Gawande and Richard F. Bradley.URSI 2007 Ottawa, Canada, July, 2007
Frequency: 0.5 to 3 GHz
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rUS SKA TDPThe TDP WBSP Feeds
•Frequency: >10:1 Bandwidth
•The -10dB HBW is ~ 65°
•Phase Center is frequency independent
•Now Compact Size ~(0.75λmax)2 x 0.2 λmax•Input Matching better than –10 dB
QSC-Feed
Novel Non Planar Ultra Wide Band Quasi Self-Complementary Antenna, Germán Cortés M. IEEE AP-S International Simposium, Honolulu, Hawaii, June, 2007
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rQSC FeedCalculated S11
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Zn=270 Ohms
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rQSC FeedCalculated VSWR
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Zn=270 OhmsZn=270 Ohms
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rQSC Feed Calculated Directivity
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rQSC FeedCalculated Prime Focus Spillover
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θ
θ [deg]
φ
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rQSC FeedCalculated Prime Focus Spillover
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θ [deg]θ [deg]
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QSC Feed Development
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rQSC Feed Development
• US SKA TDP: – Feed #1: 300 MHz to 3 GHz (room
temperature)– Feed #2: 1 to 10 GHz (cryocooled)
• Challenge: Manufacture – Feature size ratio 500:1– Differential Input (Zin~270 Ohms)
• Prototype 500 MHz to 4 GHz– Characterize QSC Feed Input Impedance– Straightforward extension to 300MHz
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rQSC Feed PrototypeInput Impedance Characterization
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rQSC Feed PrototypeInput Impedance Characterization: De-Embeding
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rQSC Feed PrototypeCoaxial Fixture de-Embeding
Open Circuit
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Open Circuit
QSC Feed PrototypeCoaxial Fixture de-Embeding
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rQSC Feed PrototypeCoaxial Fixture de-Embeding
Open Circuit Short Circuit
AUT
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rQSC Feed PrototypeInput Impedance Characterization
Coax Plug II SC-Short
Measured Data Data+Best-Fit
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rQSC Feed PrototypeInput Impedance Characterization
Coax Plug II Open Circuit
Measured Data Data+Best-Fit
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rQSC Feed PrototypeInput Impedance Characterization
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rQSC Feed PrototypeMeasured De-Embeded Differential |S11|
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Zn=270 Ohms
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rQSC Feed PrototypeMeasured De-Embeded VSWR
Zn=270 Ohms
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QSC Feed Development Timeline
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Scaled Feed Design & Prototype FabricationScaled EM Feed DesignScaled Feed Manufacture DesignScaled Feed Fabrication
Input Impedance CharacterizationCharacterization Fixture DesignCharacterization Fixture FabricationInput Impedance Measurements and Analysis
2007Q1 Q2 Q3 Q4
2008Q1 Q2 Q3 Q4
2009Q1 Q2 Q3 Q4
2010Q1 Q2 Q3 Q4
Room Temperature Feed PrototypeDevelopment
Passive BALUN DevelopmentPassive BALUN EM Design and Fabrication
Feed Pattern Measurements IMechanical Interface Design and FabricationRadiation Patterns Measurements I
Radome Design and Fabrication
Feed Pattern Measurements IINoise Temperature MeasurementsRadiation Patterns Measurements II
Active BALUN Development and Integration4-wire/twin_wire/u-strip EM launcher DesignActive BALUN Design and FabricationActive BALUN-Feed Integration
QSC Feed DevelopmentRoom Temperature Feed Prototype
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2011Q1 Q2 Q3 Q4
2008Q1 Q2 Q3 Q4
Feed Pattern Measurements IINoise Temperature MeasurementsCryostat+Feed Radiation Patterns Measurements II
2009Q1 Q2 Q3 Q4
2010Q1 Q2 Q3 Q4
Cooled UWB Feed PrototypeDevelopment
Scaled Feed Design & FabricationScaled EM Feed DesignScaled Feed Manufacture DesignScaled Feed Fabrication
Room Temp Feed Pattern Measurements IRadiation Patterns Measurements I
Cryostat Development and IntegrationCryostat EM DesignMechanical Design and FabricationCryostat Monitoring and LNA Electronics Integration
2007Q1 Q2 Q3 Q4
LNA Integration4-wire/twin_wire/u-strip EM launcher DesignActive BALUN Design and FabricationActive BALUN-Feed Integration
QSC Feed DevelopmentCooled UWB Feed Prototype
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SKA TDP Dishes + WBSPF Optics Design
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rSKA TDP Reflector + WBSP Feed Optics Design
• Detailed WBSP Feed characterization– Co-Pol and Cross-Pol Radiation Patterns– Gain– Input Matching– Losses– Phase Center Variations– Matching Optics Parameters
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rWBSP Feed ExampleFar Field Radiation Pattern 10 GHz
Co-PolDir = 10.11 dBi
X-Pol-1.08 dBi
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rSKA TDP Reflector + WBSP Feed Optics Design
• Detailed WBSP Feed characterization– Co-Pol and Cross-Pol Radiation Patterns– Gain– Input Matching– Losses– Phase Center Variations– Matching Optics Parameters
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rSKA TDP ReflectorsPossible Configurations
Symmetric Reflector Off-Axis Reflector
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Gregorian is Preferred
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rSKA TDP Reflector + WBSP Feed Optics Design
• Antenna Analysis and Design Optimization– Co-Pol and Cross-Pol Radiation Patterns– Aperture Efficiency– Antenna Temperature vs. elev & freq– Aeff/Tsys Optimization
• Matching Optics for Different Configurations– Prime Focus– Secondary Focus Solutions– Multiple Focus Solutions
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r∅8m Reflector+Baseline FeedFar Field Radiation Pattern at 700 MHz
Symmetric ReflectorCo-Pol
Symmetric ReflectorX-Pol
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r∅6m Offset Reflector+Baseline FeedFar Field Radiation Pattern at 500 MHz
Off-Axis ReflectorCo-Pol
Off-Axis ReflectorX-Pol
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rSKA TDP Reflector + WBSP Feed Optics DesignAntenna Noise Temperature vs. elev & Freq
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Antenna Noise Temperature
The Integrand:
Antenna Noise Temperature Calculations, Germán Cortés-Medellín, SKA Technical Memo Series No. 95, Oct., 2004 (at SKA site 2007)Antenna Noise Temperature Calculations, Germán Cortés-Medellín, SKA Technical Memo Series No. 95, Oct., 2004 (at SKA site 2007)
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rSKA TDP Reflector + WBSP Feed Optics DesignAntenna Noise Temperature vs. elev & Freq
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The Sky Brightness Temperature:
Atmospheric Absorption:
Cosmic Emission:
Short Formulation:
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SKA TDP Reflector + WBSP Feed Aeff/Tsys Optimization Prime Focus Symmetric Reflector
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0.2 to 2.5 GHz TRW Feed TA @ 45 deg, TRX =10 K
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rSKA TDP Reflector + WBSP Feed Optics Design
• Antenna Analysis and Design Optimization– Co-Pol and Cross-Pol Radiation Patterns– Aperture Efficiency– Antenna Temperature vs. elev & freq– Aeff/Tsys Optimization
• Matching Optics for Different Configurations– Prime Focus– Secondary Focus Solutions– Multiple Focus Solutions
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rSKA TDP Reflector + WBSP Feed Prime Focus Analysis
Symmetric Reflector Off-Axis Reflector
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rSKA TDP Reflector + WBSP Feed Prime Focus Low Frequency Analysis
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N=4500N=4500
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rSKA TDP Reflector + WBSP Feed Optics Design
• Antenna Analysis and Design Optimization– Co-Pol and Cross-Pol Radiation Patterns– Aperture Efficiency– Antenna Temperature vs. elev & freq– Aeff/Tsys Optimization
• Matching Optics for Different Configurations– Prime Focus– Secondary Focus Solutions– Multiple Focus Solutions
• PAF’s Optics + WBSPF Optics Convergence
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Summary and Concluding Remarks
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• Useful Links:
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International SKA Project http://www.skatelescope.org
International SKA Project http://www.skatelescope.org
US-SKA TDP Project http://skatdp.astro.cornell.edu
US-SKA TDP Project http://skatdp.astro.cornell.edu
Author: German Cortes gc76@cornell.edu
Author: German Cortes gc76@cornell.edu
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