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SKA-TDP AWG Antenna Workshop San Francisco, March 13-14, 2008. SKA TDP Antenna Optics. By Germán Cortés M. Cornell University Ithaca NY 14853, USA. National Astronomy and Ionosphere Center. Overview. Introduction SKA TDP Dishes + WBSPF Optics Design Plan

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Ska tdp antenna optics

SKA-TDP AWG Antenna Workshop

San Francisco, March 13-14, 2008

SKA TDP Antenna Optics

By Germán Cortés M.

Cornell University

Ithaca NY 14853, USA

National Astronomy

and Ionosphere Center


Overview
Overview

  • Introduction

  • SKA TDP Dishes + WBSPF Optics Design Plan

  • SKA TDP Antenna Work Breakdown

  • SKA TDP Baseline Antenna Optics.

  • Summary




Ska tdp dishes wbspf optics design plan
SKA TDP Dishes + WBSPF Optics Design Plan


Ska tdp reflector wbsp feed optics design plan
SKA TDP Reflector + WBSP Feed Optics Design Plan

  • Detailed WBSP Feed characterization

    • Co-Pol and Cross-Pol Radiation Patterns

    • Gain

    • Input Matching

    • Losses

    • Phase Center Variations


Wbsp feed far field radiation pattern 10 ghz
WBSP Feed Far Field Radiation Pattern 10 GHz

Co-Pol

Dir = 10.11 dBi

X-Pol

-1.08 dBi


Ska tdp reflector wbsp feed optics design plan1
SKA TDP Reflector + WBSP Feed Optics Design Plan

  • Detailed WBSP Feed characterization

    • Co-Pol and Cross-Pol Radiation Patterns

    • Gain

    • Input Matching

    • Losses

    • Phase Center Variations

    • Matching Optics Parameters


The ska tdp reflectors
The SKA TDP Reflectors

Possible Configurations

Gregorian is Preferred

Symmetric Reflector

Off-Axis Reflector


Ska tdp reflector wbsp feed optics design plan2
SKA TDP Reflector + WBSP Feed Optics Design Plan

  • 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


8m reflector baseline feed far field radiation pattern at 700 mhz
8m Reflector+Baseline FeedFar Field Radiation Pattern at 700 MHz

Symmetric Reflector

Co-Pol

Symmetric Reflector

X-Pol


6m offset reflector baseline feed far field radiation pattern at 500 mhz
6m Offset Reflector+Baseline FeedFar Field Radiation Pattern at 500 MHz

Off-Axis Reflector

Co-Pol

Off-Axis Reflector

X-Pol


Ska tdp reflector wbsp feed optics design plan3
SKA TDP Reflector + WBSP Feed Optics Design Plan

  • Antenna Analysis and Design Optimization

    • Co-Pol and Cross-Pol Radiation Patterns

    • Aperture Efficiency

    • Antenna Temperature vs. elev & freq

    • Aeff/Tsys Optimization

    • Dynamic Range Issues: Far Side Lobe Levels

  • Matching Optics for Different Configurations

    • Prime Focus

    • Secondary Focus Solutions

    • Multiple Focus Solutions


Ska offset design prime focus wide pattern wide band feed freq 1 400 ghz f 5 2m
SKA Offset Design Prime Focus: Wide Pattern Wide Band FeedFreq= 1.400 GHz, f=5.2m

-42.9 dB

-42.9 dB

-39.1 dB

-33.9 dB

-14.2 dB

-40.8 dB

Co-Polar Wide Pattern

X-Polar Wide Pattern


Far field radiation patterns including quadrupod strut diffraction effects
Far Field Radiation Patterns including Quadrupod Strut Diffraction Effects

-126 dB

-46 dB

-152 dB

-46 dB

=178°

=82°

=180°

=82°

-85 dB

-123 dB

-45 dB

-73 dB

=106°

=106°

=14°

=14°

Wide Pattern 1.3 GHz

Wide Pattern 32 GHz


Ska tdp reflector wbsp feed optics design plan4
SKA TDP Diffraction Effects Reflector + WBSP Feed Optics Design Plan

  • Antenna Analysis and Design Optimization

    • Co-Pol and Cross-Pol Radiation Patterns

    • Aperture Efficiency

    • Antenna Temperature vs. elev & freq

    • Aeff/Tsys Optimization

    • Dynamic Range Issues: Far Side Lobe Levels

  • Matching Optics for Different Configurations

    • Prime Focus

    • Secondary Focus Solutions

    • Multiple Focus Solutions


The ska tdp reflectors1
The SKA TDP Diffraction EffectsReflectors

Possible Configurations

Gregorian

Off-Axis


Ska tdp reflector wbsp feed optics design plan5
SKA TDP Diffraction Effects Reflector + WBSP Feed Optics Design Plan

  • But,… In order to do this we need to agree in some initial parameters….


Ska tdp antenna work breakdown
SKA TDP Antenna Work Breakdown Diffraction Effects


Ska tdp antenna work breakdown1
SKA TDP Antenna Work Breakdown Diffraction Effects

Science

Data

Transport

Monitoring

&

Control

UWB Feeds

Power

Optics

Reflector

Mount

Pedestal

Foundation


Ska tdp antenna work breakdown2
SKA TDP Antenna Work Breakdown Diffraction Effects

UWB Feeds

Science

Data

Transport

Optics

Monitoring

&

Control

Power

Reflector

Mount

Pedestal

Foundation


Ska tdp antenna work breakdown3
SKA TDP Antenna Work Breakdown Diffraction Effects

UWB Feeds

Optics

Reflector

Mount

Monitoring

&

Control

Power

Science

Data

Transport

Pedestal

Foundation


Ska tdp antenna work breakdown4
SKA TDP Antenna Work Breakdown Diffraction Effects

UWB Feeds

Optics


Ska tdp antenna optics specification
SKA TDP Antenna Optics Diffraction EffectsSpecification

UWB Feeds

Optics

Aeff/Tsys

Frequency

Diameter


Ska dishes wbspf technology paths
SKA Dishes+WBSPF Technology Paths Diffraction Effects

Frequency

0.07 0.2 0.5 0.8 1.5 10 GHz

1

AA’s

Dishes

Ø15m

+ WBSPF

2

AA’s

PHASE II

3b

1.5 GHz 10 GHz

PAF’s

3c

3a

Preliminary Specifications for the Square Kilometer Array

v2.7.1 Dec. 4 2007


Ska dishes wbspf technology paths1
SKA Dishes+WBSPF Technology Paths Diffraction Effects

Frequency

0.07 0.2 0.5 0.8 1.5 10 GHz

1

AA’s

Dishes

Ø15m

+ WBSPF

2

AA’s

PHASE II

3b

1.5 GHz 10 GHz

PAF’s

3c

AA’s

0.8 GHz 10 GHz

3a

Preliminary Specifications for the Square Kilometer Array

v2.7.1 Dec. 4 2007


Ska dishes wbspf technology paths2
SKA Dishes+WBSPF Technology Paths Diffraction Effects

Frequency

0.07 0.2 0.5 0.8 1.5 10 GHz

1

AA’s

Dishes

Ø15m

+ WBSPF

2

AA’s

PHASE II

3b

1.5 GHz 10 GHz

PAF’s

3c

AA’s

0.8 GHz 10 GHz

3a

0.5 GHz 10 GHz

Preliminary Specifications for the Square Kilometer Array

v2.7.1 Dec. 4 2007


Ska dishes wbspf technology paths3
SKA Dishes+WBSPF Technology Paths Diffraction Effects

Frequency

0.07 0.2 0.5 0.8 1.5 10 GHz

1

AA’s

Dishes

Ø15m

+ WBSPF

2

A

Tsys

NII

AA’s

2000

PHASE II

3b

1.5 GHz 10 GHz

70%

30K

PAF’s

2400

3c

AA’s

0.8 GHz 10 GHz

70%

30K

3000

3a

0.5 GHz 10 GHz

70%

30K

Preliminary Specifications for the Square Kilometer Array

v2.7.1 Dec. 4 2007


Ska tdp antenna optics aeff tsys point source sensitivity
SKA TDP Antenna Optics Diffraction EffectsAeff/Tsys Point Source Sensitivity

0.2

0.5

0.7

1.5

3.0

10.0

Aeff/Tsys [m2/K]

Preliminary Specifications for the Square Kilometer Array

v2.7.1 Dec. 4 2007


Ska tdp antenna optics aeff tsys point source sensitivity1
SKA TDP Antenna Optics Diffraction EffectsAeff/Tsys Point Source Sensitivity

0.2

0.5

0.7

1.5

3.0

10.0

Aeff/Tsys [m2/K]

SKA TDP


Ska tdp antenna optics tsys for a 15m dish a 70
SKA TDP Antenna Optics Diffraction EffectsTsys for a 15m Ø Dish, A =70%

0.2

0.5

0.7

1.5

3.0

10.0

SKA TDP


Ska tdp antenna optics tsys for a 15m dish a 701
SKA TDP Antenna Optics Diffraction EffectsTsys for a 15m Ø Dish, A =70%

0.2

0.5

0.7

1.5

3.0

10.0


Ska tdp antenna optics specification1
SKA TDP Antenna Optics Diffraction EffectsSpecification

Frequency

0.07 0.2 0.5 0.8 1.5 10 GHz

UWB Feeds

0.5 GHz 10 GHz

Optics

Aeff/Tsys

Frequency

Diameter


Ska tdp antenna optics specification2
SKA TDP Antenna Optics Diffraction EffectsSpecification

Frequency

UWB Feeds

0.07 0.2 0.5 0.8 1.5 10 GHz

0.5 GHz 10 GHz

Optics

Aeff/Tsys

Frequency

Diameter


Ska tdp antenna optics specification3
SKA TDP Antenna Optics Diffraction EffectsSpecification

Frequency

UWB Feeds

0.07 0.2 0.5 0.8 1.5 10 GHz

0.5 GHz 10 GHz

Optics

Room Temp

0.3 3 GHz

Cooled

1.0 GHz 10 GHz

Aeff/Tsys

Frequency

Diameter


Ska tdp antenna optics specification4
SKA TDP Antenna Optics Diffraction EffectsSpecification

Frequency

UWB Feeds

0.07 0.2 0.5 0.8 1.5 10 GHz

0.5 GHz 10 GHz

Optics

Room Temp

0.3 3 GHz

Cooled

1.0 GHz 10 GHz

Aeff/Tsys

6 8 10 12 14 16 Ø [m]

Frequency

10 m  16 m

Diameter


Ska tdp antenna optics specification5
SKA TDP Antenna Optics Diffraction EffectsSpecification

Frequency

UWB Feeds

0.07 0.2 0.5 0.8 1.5 10 GHz

0.5 GHz 10 GHz

Optics

Room Temp

0.3 3 GHz

Cooled

1.0 GHz 10 GHz

Aeff/Tsys

6 8 10 12 14 16 Ø [m]

Frequency

10 m  16 m

Diameter

Survey Speed

Point Source

Sensitivity


Prime focus aeff tsys vs frequency for na 4500
Prime Focus Diffraction EffectsAeff/Tsys vs. Frequencyfor Na=4500

Reflector 12m

Reflector 8m

Reflector 6m



Ska tdp reflector wbsp feed baseline optics design plan
SKA TDP Diffraction Effects Reflector + WBSP Feed Baseline Optics Design Plan

  • Baseline Optics Designs that uses WBSPF

  • Diameter: 12 m to 16 m

  • Frequency: < 0.5 GHz to 10 GHz

  • 1st Step: Optimized Aeff/Tsys Optics Design for a Symmetric Configuration:

    • Prime Focus WBSPF: 0.3 GHz to 3 GHz

    • Secondary Focus WBSPF: 1 to 10 GHz

  • 2st Step: Optimized Aeff/Tsys Optics Design for a Off-axis Configuration


Ska tdp reflector wbsp feed optimized prime focus
SKA TDP Diffraction Effects Reflector + WBSP Feed Optimized Prime Focus

  • Diameter: 16 m

  • WBSPF 0.3 to 3 GHz

  • f1/D Optimized for for Aeff/Tsys

12 m

16 m


Ska symmetric antenna a eff t sys prime focus optimization using uwb feed
SKA Symmetric Antenna Diffraction EffectsAeff/Tsys Prime focus Optimization using UWB Feed

([email protected]°, Trx=10K, Freq: 0.5 GHz to 2.5 GHz)

53°


Ska symmetric antenna a eff t sys prime focus optimization using uwb feed1
SKA Symmetric Antenna Diffraction EffectsAeff/Tsys Prime focus Optimization using UWB Feed

([email protected]°, Trx=10K, Freq: 0.5 GHz to 2.5 GHz)

79°

64°

53°


Ska tdp reflector wbsp feed optimized prime focus1
SKA TDP Diffraction Effects Reflector + WBSP Feed Optimized Prime Focus

  • Diameter: 16 m

  • WBSPF 0.3 to 3 GHz

  • Optimized for for Aeff/Tsys: f1/D ~ 0.38

12 m

16 m


Ska tdp reflector wbsp feed optimized secondary focus
SKA TDP Diffraction Effects Reflector + WBSP Feed Optimized Secondary Focus

  • Diameter: 12 m

  • WBSPF 1 to 10 GHz

  • Optimized for for Aeff/Tsys: f2/D > f1/D

12 m


Ska tdp reflector wbsp feed optimized secondary focus1
SKA TDP Diffraction Effects Reflector + WBSP Feed Optimized Secondary Focus

  • Diameter: 12 m

  • WBSPF 1 to 10 GHz

  • Optimized for for Aeff/Tsys: f2/D > f1/D

  • Shaped Optics is also an option for this frequency band.

12 m


Ska tdp reflector wbsp feed optimized multiple focus
SKA TDP Diffraction Effects Reflector + WBSP Feed Optimized Multiple Focus

  • Prime Focus Ø16 m

  • WBSPF 0.3 to 3 GHz

  • Optimized for for Aeff/Tsys: f1/D ~ 0.38

  • Secondary Focus Ø12 m

  • WBSPF 1 to 10 GHz

  • Optimized for for Aeff/Tsys: f2/D > f1/D

12 m

16 m


Ska technology path
SKA Technology Path Diffraction Effects

TDP WBSP Feeds

Wide Band

Feeds

Bandwidth

10dB

TN

Input

Match

5:1 10:1 20:1

62°

Chalmers

~10:1

-7 dB

4 - 12 GHz

66°

30K

Quad-Ridge

~8:1

-6 dB

65°

Sinuous/Gnd

~10:1

-8 dB

65°

QSC Feed

-10 dB

~15:1

1 - 7 GHz

43°

45K

ATA

>20:1

-14 dB


Summary
Summary Diffraction Effects

  • We are proposing a Frequency coverage for the SKA TDP that goes from < 0.5 to 10 GHz, and that uses WBSPF + Dishes.

  • TDP is going to provide two WBSP feeds that demonstrate the performance of these feeds:

    • One at room temperature from 0.3 to 3 GHz.

    • One Cooled feed from 1 to 10 GHz.


Summary cont
Summary Cont… Diffraction Effects

  • We proposed a dish diameter between 12m to 16 m. And still have to agree in a dish diameter for the electromagnetic analysis.

  • We are going to provide an antenna analysis and optimization for baseline symmetric and off-axis prime focus configurations that uses WBSP feeds.

  • We are going to analyzed options for secondary or multiple focal point configurations.

  • We are going to assess the issue of the far SLL for Dynamic Range.


End Diffraction Effects


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