OPS Forum Cryo Systems ESTRACK 16.10.2000

S.Halte, OPS-GSS, 16/10/09

1

Cryogenic Receivers:

Closer to the noise floor

Present and future of Cryogenic Receivers in ESTRACK


2

About Myself

Ground Station engineering division / RF and signal processing section.

– Cryogenic receivers/ amplifiers– Frequency converters (Ka band deep space up/down converters)– Radiometer.– Studies with European universities– DSA3– SSA radar development


3

Introduction

– What is a Receiver?• an electronic device that changes a radio signal from a transmitter into

useful information

– What does Cryogenics deal with?• The word cryogenics comesfrom Greek and means "the production of

freezing cold“. It is commonly admitted that the field of Cryogenics covers range of temperature below -180 °C (Nitrogen boiling temperature).

– Why cryogenic receiver?• Because during propagation a radio signal is affected by external

perturbation. In particular noise created by cosmic radiation and thermal noise due to the particles random movement. Cooling down the devices reduces this noise drastically.


4

Introduction

How a deep space telemetry signal is propagated.

Very Low noise Technology.

Cryogenic technology

Deep space cryogenic receivers and improvements

Compact, miniaturized cryogenics Low Noise Amplifiers

Future developments


5

Deep space telemetry

P transmit= 28 W

Ant diameter = 2.2 m

Distance= 500 million km

Ant diameter = 35 mP receive= 1x10- 16 Watt (0.0000000000000001 W)


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Noise in space communication

Ground Noise

Cosmic noiseSun noise

Clouds + rain noise

Atmosphere noise Antenna noise

Total sky noise and antenna noise power= 1 x 10 -17 W (16 zero after the point)


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Noise in electronic equipment

Sun

Earth

Atmosphere

ReceiverOutput

LNA

Resistive loss

Standard amplifier: Receiver Noise = 2x10-15 W


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Signal over Noise Ratio

Signal 1x10-16 W Antenna + Atmosphere Noise 1x10-17 W Receiver Noise 1x10-17 W

----------------------------------------

Signal/Noise 5 (7dB)


9

Very low noise amplifiers

The noise power generated by a standard amplifier and receiver thermal noise is higher than the signal power to recover…

Need to develop very low noise amplifier using:– Very low noise transistor technology– Cool down the receiver in order to decrease the thermal noise

Deep Space antenna uses High Electron Mobility Transistors cooled down at 15K in order to be able to retrieve deep space signal from the noise


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High Electron Mobility Transistors


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InP Technology


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InP Technology

GaAs (gallium arsenide ) transistors are widely use in the Telecom industry and can be provided easily by standard manufacturers (Mitsubishi)

InP technology is not available from standard manufacturer and was only available in USA but protected by ITAR regulation.

It has been necessary to develop InP devices in X and Ka band with European universities in order to minimize the receiver noise.


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InP Transistors


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X band Low Noise Amplifier


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Ka band low noise amplifier


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Cryogenic cycle

Heat removed from outside

Heat transferred outside

PV=cstxT


17

Vacuum Dewar: Heat transport mechanism

Convection

Conduction

IR Radiation

Gas molecule

Vacuum Enclosure

Cooled Sample, cryogenic temperature

Sample support structure

Dewar wall

Convection, conduction, radiation

How to reduce these thermal loads ?

Convection: remove physical support = air molecules = process vacuum (pressure <10-3 mbar) inside the Dewar.

Conduction: Remove physical support when possible (i.e. process vacuum); select material with low thermal conductivity at operational temperature.

Radiation: Use Infra-Red reflective materials such as MLI (Multi-Layer Insulations) to stop radiations. Select material with low emissivity factors to reduce absorption of IR at operational temperature.


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Cryogenic Receiver in Deep Space Antennas

- 2 S- Band in New Norcia

-4 X- Band in New Norcia and Cebreros

-2 Ka Band in Cebreros


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Cryogenic Receiver


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Cryogenic receiver


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Gain and noise performance (room/ cryo)

Equivalent Noise Temperature: 11K

Pnoise=1.2 x10 -17 W

Gain=57 dB

Signal is amplified 1 000 000 times


22

S Band Cryogenic Receiver


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Ka Band multichannel Receivers


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In the Antenna Equipment Room


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Reliability

0

2

4

6

8

10

12

14

1000 3000 5000 7000 9000 11000Running time before failure (hours)

Nd

of

fail

ure

s


26

Maintainability

Time to cool down = 7 hours Time to warmup = 12 hours Time for repair= 3 hours Test = 2 Warmup / cool down cycle to

declare the system operational

The system is unavailable for 41 hours minimum during servicing/repair


27

Reliability and maintainability improvement

High vacuum is difficult to maintain and needs regular pumping– Replace vacuum insulation with new generation solid insulator

(aerogel) The cryocooler is not reliable as a lot of failures occurs before the

recommended maintenance period– Change cryocooler with a more reliable solution: Summitomo

cryocooler is used in 90% of medical magnetic imaging machines In case of failure the exchange or repair of the cooler has to be

done by specially qualified staff and is very time consuming.– Implement a cold head sleeve for rapid exchange of the cooler– Implement heaters in order to reduce the warmup time to 2 hours


28

Cold head sleeve


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Aerogel

nanotechnology product = dried silica gel

nullify three methods of heat transfer:

Convection: aerogel is a closed lattice and thus limits air convection

Radiation: aerogel selected is IR opacified to stop radiations

Conduction: . @ atmospheric pressure, aerogel is one of the most insulative material ever


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Second generation


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Thermal simulation


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Kourou cryogenic LNA


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Kourou cryogenic LNA Integration


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Miniaturized cryogenic LNA


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Miniaturized cryo LNA

RF housing For the MMIC


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Microwave Monolithic Integrated Circuit


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Miniaturized cryogenic LNA


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Data rate limitation


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DSN array (JPL)


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DSN Array (JPL)


41

X Ka band cryogenic receiver

Dual frequency feed

31-38 GHz Ka LNAs

8-8.8 GHz X LNAs

15 K refrigerator


42

Conclusion

Next generation of cryogenic receiver will include all the passive elements in front of the Low Noise Amplifier to lower thermal noise.

New technology of low noise amplifier to be developed for high frequency (SiC, GaP)

Cryogenic receiver will be included in arrays antenna to increase the gain and reduce the noise simultaneously

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