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15-16 April 2010 Lynn Baker DVA-1 Meeting at NSFLynn Baker DVA-1 Meeting at NSF 1
Wideband Single Pixel Feeds
DVA-1 Project
Lynn Baker
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15-16 April 2010 Lynn Baker DVA-1 Meeting at NSFLynn Baker DVA-1 Meeting at NSF 2
TDP Broadband Feed Development GoalsTDP Broadband Feed Development Goals
• Research and prototype feeds with bandwidths up to 10:1 with high performance when mounted in reflector antennas.
• Develop matching wide band LNA’s closely integrated with the corresponding feed.
• Develop supporting cryogenic cooling methods and designs.
• Other research groups pursuing similar goals.
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15-16 April 2010 Lynn Baker DVA-1 Meeting at NSFLynn Baker DVA-1 Meeting at NSF 3
Baseline Frequency Coverage PlanBaseline Frequency Coverage Plan
• Cover .3 to 1.5 GHz with an uncooled feed with cooled LNA1. Low freqency feed is to too large to cryocool2. Thermal transition on transmission line challenging
• Cover 1.5 to 10 GHz. with a completely cooled feed / LNA1. All cryocooled practical at higher frequencies
• PAF mounted at prime focus with interchange mechanism
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15-16 April 2010 Lynn Baker DVA-1 Meeting at NSFLynn Baker DVA-1 Meeting at NSF 4
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15-16 April 2010 Lynn Baker DVA-1 Meeting at NSFLynn Baker DVA-1 Meeting at NSF 5
Cal Tech Feed / LNA UpdateCal Tech Feed / LNA Update
• Three “Lindgren” style feeds built & measured, feed patterns measured both open and in a dewar can, two installed on the GAVRT antenna.
• Data posted to feed pattern data base.• Continued development of differential LNA’s matched to
feed characteristics.• Improved versions are under construction, both in LNA
interface and in radiation pattern.
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15-16 April 2010 Lynn Baker DVA-1 Meeting at NSFLynn Baker DVA-1 Meeting at NSF 6
ATA Log-periodic FeedATA Log-periodic Feed
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15-16 April 2010 Lynn Baker DVA-1 Meeting at NSFLynn Baker DVA-1 Meeting at NSF 7
ATA Log-periodic FeedATA Log-periodic Feed
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15-16 April 2010 Lynn Baker DVA-1 Meeting at NSFLynn Baker DVA-1 Meeting at NSF 8
ATA Log Periodic UpdateATA Log Periodic Update
• Original design modeled in CST and calculated patterns included in TDP feed pattern data base.
• Two versions of an improved feed are almost finished. One will be tested at Cal Tech and one at ATA facilities.
• The new ATA version will be housed in a glass dewar and cryocooled. It also has a redesigned feed to LNA connection.
• The new Cal Tech version will be housed in a metal dewar and cryocooled. Also has improved feed to LNA connection.
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15-16 April 2010 Lynn Baker DVA-1 Meeting at NSFLynn Baker DVA-1 Meeting at NSF 99
The Ultra Wide Band QSC FeedThe Ultra Wide Band QSC Feed 300 MHz to 3 GHz Prototype 300 MHz to 3 GHz Prototype
Truncated Ground plane to 500 MHz for Initial testing: low frequency extension straightforward
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15-16 April 2010 Lynn Baker DVA-1 Meeting at NSFLynn Baker DVA-1 Meeting at NSF 10
QSC Feed UpdateQSC Feed Update
• Original model measured at Satimo and pattern data posted to the data base.
• Second version designed and model patterns calculated both with and without a simulated dewar can.
• Pattern data posted to data base.• Design work under way on a higher gain version and for other
frequency bands.
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15-16 April 2010 Lynn Baker DVA-1 Meeting at NSFLynn Baker DVA-1 Meeting at NSF 11
Broadband Feed Trade Off & Risk MitigationBroadband Feed Trade Off & Risk Mitigation
• DVA-1 will provide a test bed to evaluate wide band feeds.• One (or more) corrugated horns will be mounted and tested in
DVA-1• Combined with pricing for receiver packages these results
will inform tradeoffs between performance, frequency coverage and cost.
• Input from calibration and processing will be critical in evaluating feed options.