Antenna Optical Design and Wide Band Feed Development for the … · 2008. 11. 3. · Antenna...

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

© Germán Cortés M 2008

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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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Cost Function Analysis

Parabolic Dishes,David DeBoer, France, Sep 2006Parabolic Dishes,David DeBoer, France, Sep 2006

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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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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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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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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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•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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•The -10dB HBW is ~ 65°


•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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•Frequency: >10:1 Bandwidth

•The -10dB HBW is ~ 65°


•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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Coax Plug II SC-Short

Measured Data Data+Best-Fit

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Coax Plug II Open Circuit

Measured Data Data+Best-Fit

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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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• 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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• 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 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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• 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 [email protected]

Author: German Cortes [email protected]

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End

Antenna Optical Design and Wide Band Feed Development for the … · 2008. 11. 3. · Antenna...

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Transcript of Antenna Optical Design and Wide Band Feed Development for the … · 2008. 11. 3. · Antenna...