EVLA Front-End CDR

Brent Willoughby EVLA Front-End CDR – WVR Option24 April 2006

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EVLA Front-End CDR

Water Vapor RadiometerOption


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Water Vapor Radiometer

• Development project

• Not in EVLA baseline plans

• If successful, has implications for EVLA


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


4

Current WVR system

• 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

(From Butler 1999)


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


6

VLA WVR block diagram


7

WVR prototype stability

measurements, using a K band noise diode as

source


8

Baseline length = 800 m, sky clear, 22 GHz

Baseline length = 2.5 km, sky cover 50-75%, forming cumulus, 22 GHz

Correlation between phase and WVR output for two VLA antennas

*BLUE: Phase corrected using the scaled WVR output*RED: Uncorrected phase*GREEN: Scaled WVR output


9

EVLA Compact WVR

Prototype 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


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CWVR MMIC

• 15 MMIC chips

• 23 chip caps

• 7 circuit substrates

• 110 wire bonds

• 30% initial savings vs. connectorized version


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EVLA K-Band with Compact WVR(Multiplexed Dual Channel)

LO

Ref

35dB

RC

P I

F O

ut8-

18 G

Hz

18-26GHz

NoiseDiodePol

LNA

Old

New

29-37 GHz 0 dBm18 dBm

x2Doubler

x2Doubler

Dewar

RF/IF Box

NRAOCDL

35dB

LNA

NRAOCDL

PamtechKYG2121-K2

(w/g)

PamtechKYG2121-K2

(w/g)

Noise/COMNC 5242

(w/g)

8-16 GHz

Some New

8-16 GHz

32dB

K&L Filter13FV10-

22250/U8500

MICAT-318S30

QuinstarQLN-2240J0Po>+10dBmNF < 2.5 dB

MICAT-318S20

MICAT-318S30

LC

P I

F O

ut8-

18 G

Hz

15-1

8 G

Hz

NordenDoubler

DitomDF2806

13.5-21.5GHz

MAC TechPA82072H (2F)13.5-21.5 GHz

(16.0-19.3 GHz)

Krytar6020265

2-26.5 GHz

WVR Box

TemperatureStabilized Plate

RCP

LCP

TCal WR-42To

SMA

MDL42AC206

AtlanticMicrowave

AB4200

Com

pact

WV

R

10 dB

32dB10 dB

MICAT-318S20

Krytar262210

MICAT-318S20

K&L Filter13FV10-

22250/U8500

MICAT-318S30

QuinstarQLN-2240J0Po>+10dBmNF < 2.5 dB

MICAT-318S20

MICAT-318S30

MICAT-318S20

Krytar262210

MiteqTB0440LW1 Po>+9dBmCL < 10dB

MICAT-318S20

MICAT-708S40

MICAT-708S35

TTT FilterK4906-8-16.5G

MiteqTB0440LW1 Po>+9dBmCL < 10dB

MICAT-318S20

MICAT-708S40

MICAT-708S35

TTT FilterK4906-8-16.5G

03

dB

m


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Prototype Compact WVR

35dB

19.25 / 1.50 GHz

21.00 / 0.75 GHz

22.25 / 1.00 GHz

23.50 / 0.75 GHz

25.25 / 1.50 GHz

DC

DC

DC

DC

DC

F = 19.25

F = 21.00

F = 22.25

F = 23.50

F = 25.25

Frequency Multiplexer

0, 3 & 6 dBIL = 3 dB

PO > 15 dBm

MatchedDetectors

DC AmpGain ~ 50

Termination

LCP In

“Dark Current”Switch

Input ModeSwitch

DigitalAttenuator

(ChopperStabilized)

(Linearity &Temp)IL = 2.5 dB

IL = 1.5 dBPO > 15 dBm

NF < 5 dBPO > 20 dBm

IL = 1.5 dBPO > 15 dBm

RCP Inor

Termination

DigitalAttenuator

0, 3 & 6 dBIL = 3 dB

PO > 15 dBm

FixedPad

(Optional)

SecondPost-amp


13

Matt Morgan’s MMIC Module

5 channelV-F

FIBER OUTPUTS

MMMMICM

Noise Diode

19.25/1.50 GHz

21.0/.75 GHz

22.25/1.0 GHz

23.5/.75 GHz

25.25/1.5 GHz

RCP

LCP

18-26.5GHz

Pol

35 dB

35 dB

LNA

LNA

MMIC BLOCKKBANDRCVR

RF POSTAMPS/FILTERSK&L

FILTER22250/U8500

IsolatorMICA

T-318S50

QUINSTARAmplifier

QLN-2240J0

32 dB

32 dB

10dB

10dB

V/F

V/F

V/F

V/F

V/F

0-2 MHz OUT

FIBEROPTICXMIT

VOLTAGE TO FREQUENCY PCB

TO F318TEC

FIBEROPTICRCVRS

DIGITALCOUNTER

NOISEDIODE

MPT-5000 Temp Controller

To V/F0-10V out

FROM MMIC0-10 VDC IN

0–2 MHz IN

9.6 Hz Cal Switching 1 Hz 19.2 Hz

ANALOGSIGNAL

CONDITIONER

Outside Temperature ProbeOuter CWVR Temperature Probe

TEC Plate Temperature Probe

ANALOG CARD

MIB

F318

CWVR BLOCK DIAGRAM 07/28/04

2nd Postamp

35 dBLCP

RCP

Tcal

TO I.F.

TO I.F.

MULTIPLEXER

EVLA CWVR


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EVLA K-BandImpact of WVR on Rx Performance (with TLNA=10°K)

T(LNA) = 10K

Dewar Receiver Output RF Box WVRTn Tn P HR (1%) Adds Tn P HR(1dB)(K) (K) (dBm) (dB) (K) (K) (dBm) (dB)

EVLA K-Band Rx - No WVR 21.22 22.56 -37.0 21.2 1.35 - - -

EVLA K-Band Rx - With Compact WVR 21.22 22.57 -39.0 22.2 1.35 22.67 -27.5 23.2

Required Spec - - -40.0 > 20 - - -25.0 > 16

Delta Tn (wrt to Trx ) = Percent Difference between Noise Temperature at the Sampler Input compared to that at the Receiver OutputGoal = 1% (ie: S/N of 20 dB)

Delta Tn (wrt to Dewar) = Percent Difference between Noise Temperature at the Sampler Input compared to that at the Dewar OutputGoal = < 5%

Headroom (Rx) = Ratio in dB below the 1% Compression Point (typically 12 dB below 1 dB Compression Point)Goal = 20 dB

Headroom (WVR) = Ratio in dB below the 1 dB Compression Point


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Preliminary CWVR data


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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

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EVLA Front-End CDR

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