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EVLA Front-End CDR

EVLA Front-End CDR. Water Vapor Radiometer Option. Water Vapor Radiometer. Development project Not in EVLA baseline plans If successful, has implications for EVLA. WVR….why?.

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EVLA Front-End CDR

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  1. EVLA Front-End CDR Water Vapor Radiometer Option EVLA Front-End CDR – WVR Option 24 April 2006

  2. Water Vapor Radiometer • Development project • Not in EVLA baseline plans • If successful, has implications for EVLA EVLA Front-End CDR – WVR Option 24 April 2006

  3. WVR….why? • Water vapor emission in the atmosphere increases electrical path length resulting in phase fluctuations in the astronomical data • The effect of these fluctuations is greater at shorter wavelengths • Measuring fluctuation of the amplitude of water vapor emission at 22 GHz enables a phase correction to be generated and applied to astronomical data EVLA Front-End CDR – WVR Option 24 April 2006

  4. The current WVR detection scheme uses three channels centered on the water line The bandwidth and frequency of the channels are limited by RFI generated in the present LO scheme Current WVR system (From Butler 1999) EVLA Front-End CDR – WVR Option 24 April 2006

  5. ScientificRequirements • Defined by need to measure Q band phase fluctuations to 10 deg rms • Fractional amplitude stability of 10–4 • Timescales 2 sec to 30 min EVLA Front-End CDR – WVR Option 24 April 2006

  6. VLA WVR block diagram EVLA Front-End CDR – WVR Option 24 April 2006

  7. WVR prototype stability measurements, using a K band noise diode as source EVLA Front-End CDR – WVR Option 24 April 2006

  8. Correlation between phase and WVR output for two VLA antennas Baseline length = 800 m, sky clear, 22 GHz Baseline length = 2.5 km, sky cover 50-75%, forming cumulus, 22 GHz *BLUE: Phase corrected using the scaled WVR output *RED: Uncorrected phase *GREEN: Scaled WVR output EVLA Front-End CDR – WVR Option 24 April 2006

  9. EVLA Compact WVRPrototype Module • The Compact WVR concept uses an integrated module with MMIC and drop-in devices (amps, switches, detectors) and microstrip filters • Cheaper than a connectorized version • Smaller size & less mass • Better thermal stability • Easier to mass produce • More frequency bands (5 filters rather than 3) • “Dark Current” switch allows DC offsets to be determined • Input switch allows selection between LCP & RCP signals or between Rx & a Termination (or Noise Source) for calibration EVLA Front-End CDR – WVR Option 24 April 2006

  10. CWVR MMIC • 15 MMIC chips • 23 chip caps • 7 circuit substrates • 110 wire bonds • 30% initial savings vs. connectorized version EVLA Front-End CDR – WVR Option 24 April 2006

  11. EVLA K-Band with Compact WVR(Multiplexed Dual Channel) Dewar MICA T-318S30 K&L Filter 13FV10- 22250/U8500 MICA T-318S30 Quinstar QLN-2240J0 Po>+10dBm NF < 2.5 dB Miteq TB0440LW1 Po>+9dBm CL < 10dB MICA T-708S40 TTT Filter K4906- 8-16.5G MICA T-318S20 Krytar 262210 MICA T-318S20 MICA T-318S20 MICA T-708S35 RCP IF Out 8-18 GHz RF/IF Box Pamtech KYG2121-K2 (w/g) NRAO CDL WVR Box 10 dB 32dB RCP 35dB 8-16 GHz Temperature Stabilized Plate LNA Ditom DF2806 13.5-21.5 GHz 15-18 GHz x2 18-26 GHz Atlantic Microwave AB4200 Noise/COM NC 5242 (w/g) MICA T-318S20 MDL 42AC206 Doubler TCal Compact WVR Pol WR-42 To SMA Noise Diode 18 dBm 29-37 GHz 0 dBm 03 dBm Krytar 6020265 2-26.5 GHz x2 MAC Tech PA82072H (2F) 13.5-21.5 GHz (16.0-19.3 GHz) LO Ref Doubler Norden Doubler LNA 8-16 GHz 35dB LCP 32dB 10 dB Pamtech KYG2121-K2 (w/g) NRAO CDL Old LCP IF Out 8-18 GHz MICA T-318S30 K&L Filter 13FV10- 22250/U8500 MICA T-318S30 Quinstar QLN-2240J0 Po>+10dBm NF < 2.5 dB Miteq TB0440LW1 Po>+9dBm CL < 10dB MICA T-708S40 TTT Filter K4906- 8-16.5G MICA T-708S35 MICA T-318S20 Krytar 262210 MICA T-318S20 MICA T-318S20 Some New New EVLA Front-End CDR – WVR Option 24 April 2006

  12. Prototype Compact WVR Frequency Multiplexer Fixed Pad Digital Attenuator Matched Detectors DC Amp Gain ~ 50 LCP In DC F = 19.25 19.25 / 1.50 GHz Input Mode Switch Digital Attenuator Second Post-amp “Dark Current” Switch DC 21.00 / 0.75 GHz F = 21.00 35dB 22.25 / 1.00 GHz DC F = 22.25 NF < 5 dB PO > 20 dBm 0, 3 & 6 dB IL = 3 dB PO > 15 dBm IL = 1.5 dB PO > 15 dBm IL = 1.5 dB PO > 15 dBm DC 23.50 / 0.75 GHz F = 23.50 Termination 25.25 / 1.50 GHz DC F = 25.25 RCP In or Termination (Chopper Stabilized) (Optional) (Linearity &Temp) 0, 3 & 6 dB IL = 3 dB PO > 15 dBm IL = 2.5 dB EVLA Front-End CDR – WVR Option 24 April 2006

  13. Matt Morgan’s MMIC Module MMMMICM 5 channel V-F Noise Diode FIBER OUTPUTS EVLA Front-End CDR – WVR Option 24 April 2006

  14. EVLA CWVR

  15. EVLA K-BandImpact of WVR on Rx Performance (with TLNA=10°K) EVLA Front-End CDR – WVR Option 24 April 2006

  16. Preliminary CWVR data EVLA Front-End CDR – WVR Option 24 April 2006

  17. Future CWVR plans • Continue evaluating MMIC module in the lab using a noise source and then a K band receiver • Evaluate RFI environment in an EVLA antenna to determine filter bandpasses • Design/Test 5 channel MIB interface • Contingent on funding and manpower EVLA Front-End CDR – WVR Option 24 April 2006

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