Paul Lilie EVLA Front-End CDR – Solar ModeApril 24, 2006

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EVLA Front-End CDR

Solar Mode

Paul Lilie EVLA Front-End CDR – Solar ModeApril 24, 2006

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Solar Power Levels

• 1 SFU = 104 Jy = 1250 Kelvins at VLA

• Max. flare = 100,000 SFU

• “Normal” Tsys ~~ 25 K = 0.02 SFU

• Max/Normal = 67 dB range.

• Receivers & Noise “Cal” must accommodate 67 dB range.

Paul Lilie EVLA Front-End CDR – Solar ModeApril 24, 2006

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Generic Receiver(One Polarization Shown)

LNA

PolarizerNoise Diode

Paul Lilie EVLA Front-End CDR – Solar ModeApril 24, 2006

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Generic Receiver(One Polarization Shown)

LNA

PolarizerNoise Diode

Paul Lilie EVLA Front-End CDR – Solar ModeApril 24, 2006

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Generic ReceiverSolar Additions

LNA

Polarizer

HNA

Noise Diode

Paul Lilie EVLA Front-End CDR – Solar ModeApril 24, 2006

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New Components Required

• “High Noise” amplifier (2)

• SPDT RF switch (2)

• Steppable (vs. fixed) attenuator (1)

Paul Lilie EVLA Front-End CDR – Solar ModeApril 24, 2006

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Amplifier Power Out

Amplifier Power Outputs

-70

-60

-50

-40

-30

-20

-10

0

-1 0 1 2 3 4 5 6 7 8

Log Tsource

dB

m

LNA

LNA Compr.

HNA

HNA Compr.

1 Jy

300K

Quiet Sun

Active Sun

Flare

Paul Lilie EVLA Front-End CDR – Solar ModeApril 24, 2006

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Additional Requirements

• Requires accurate “cal” values.

• Requires phase transfer between modes.

Paul Lilie EVLA Front-End CDR – Solar ModeApril 24, 2006

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Conclusions

• No compromise of “normal” observing.

• Accommodates wide input range.

• Few additional components.

• Can be added later without major rebuild.