SKA

1
Active Antenna Design and Characterization

• Jan Geralt Bij de Vaate
• Bert Woestenburg
• Laurens Bakker
• Roel Witvers
• Erik van der Wal
• Oscar Alberto Garcia Perez (CarlosIII, Madrid)

2
SKA

• Active antennas
• Sparse aperture array 70-400MHz
• 4000 m2/K, Tsys1000 4 km2
• 2 million Antennas
• Dense aperture array 300-1200MHz
• 10.000 m2/K, Tsys40K 0,7 km2,
• 45 million Antennas
• Aperture efficiency 80, 45 degree scan

• Worth optimizing cost and performance

3
Why active antennas

• Differential LNA will match directly the
  differential antenna
• Antenna impedance match ? 50O

4
Noise budget

• TLNA 30 of noise budget only

5
300K

• Cryogenic cooling not possible (s!)
• And not needed!?
• Just a wide band matching issue?!
• Providing fT gt 100GHz
• mHEMT GaAs, CMOS

6
Aperture Array Tsys

• TDirect part Reflected part coupled part
• Optimum Noise match if

7
An antenna system simulator
8

• Besides low Tmin
• Low RN
• Or better low N RN Gopt (power match!)
• Large transistors
• SiGe transistorswith very ß?

9
Second generation APERTIF LNA

• Feed integrated with LNA
• Design for 50ohm input impedance
• HPF with 25dB attenuation at 800MHz
• LNA based on Avago 54143

10
Noise measurements

• Liquid nitrogen gives a up to 5K better results
• But also some points up to 10K worse
• with connector at input

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Avago 35143 differential LNA

• 150 Ohm input impedance

Oscar Perez 09
12
Noise parameter measurements

• Maury tuner
• Agilent PNA-X
• Commercial Maury software
• Both hot/cold and cold method possible
• Different algorithms to determine noise parameters

13
New GaAs components

• OMMIC mHEMT 150GHz fT

14
Hot cold test facility THACO
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Antenna Al Vivaldi radiatorPAFs APERTIF

• Measured 52K Trec (incl Tsky)

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Differential antenna

• Single layer polyester foil

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Differential Active Antenna

• 60K
• 70nm mHEMT

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Complete tile

20
RFI

• Heats up the cold

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Conclusion (1)

• AA ground work done on
• Room temp LNAs (technologies, approaches)
• Active arrays
• EMBRACE, 2-PAD, FIDA3, FLOWPAD3
• SKA readiness tile requires AAVP effort
• Antenna concept
• LNA technology

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Conclusion (2)

• More focused effort required on room temperature
  LNAs
• SKA UMAN, ASTRON, OPAR, XLIM, CSIRO, Calgary,
  Caltech, CarlosIII, Chalmers
• Low frequency transistor modeling
• UMAN and ASTRON will combine efforts in AAVP
• Technology choice, CMOS/GaAs/SiGe still not clear
• Close to 50K Tsys
• 40K achievable