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OPS Forum ESTRACK Transmitters 25.09.2009

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Satellite telecommunication links cover astounding distances; ESA missions need to communicate with spacecraft orbiting at distances up to 900 million kilometres away. The uplink signal must be strong enough to travel these enormous distances and still deliver data to a satellite's receiver. High Power Amplifiers (HPAs) are used at ESA ground stations to provide the requisite high power levels required for the uplink. HPAs have certain distinctive characteristics. They are heavy (up to 1500 kg), energy intensive (up to 100 kW) and they must be handled with a lot of care - any mishandling can lead to severe damage not only to the amplifier itself but also to the station - or, in the worst case, even cause serious injuries or death station personnel. This forum provides a short introduction to high-power amplifiers and their technology, to solid state power amplifiers, why we still use klystrons (a vacuum tube invented in the 1930s) and the usage of HPAs at ESA ground stations.

Text of OPS Forum ESTRACK Transmitters 25.09.2009

  • 1. Power amplifiers: The last kingdom of Vacuum Tubes Present and future of Power Amplifiers in ESTRACK

2. About .

    • This is a forum about Hardware, not only hard, but also heavy, bulky and (when working) very hot!
    • We will talk about Transistors and also vacuum tubes (in the XXI stcentury!)
    • No acronyms (OK, only three: HPA, SSPA and KPA)
    • No formulas
    • A lot of pictures, so
    • Enjoy the show!

3. What is a power amplifier

  • Provides to the RF signal the required power level to reach the satellite with enough strength
  • Transform electrical power (from mains supply) into RF power
  • Capital performance: Efficiency
  • High power handled -> High power consumed and dissipated
  • The consumed power not transformed in RF power shall be dissipated
  • Limitations may come from maximum electrical field (peak power) or maximum thermal dissipation (average power)

4. What happens if we dont take care 5. Why we need a power amplifier

  • High power required to compensate path losses over 100s million kilometres (Mars is between 50 and 400 million km) -> 270 dB of signal attenuation in the path.
  • How much power is received?
    • Transmission of 20 kW
    • X Band (7.190 MHz)
    • Power focused in a narrow beam(64 dB gain of a 35m antenna)
    • Satellite antenna of 0.8 meters (33 dB antenna Gain)
    • Total power collected by the antenna: -100 dBm!! That is 0.1 pWatts
    • And this is not the worst case!

6. Where is the power amplifier

  • New Norcia

7. Types of Power amplifiers

  • HPA: High Power Amplifier
  • SSPA: Solid State Power Amplifier
  • KPA: Klystron Power Amplifier
  • Magnetrons, Travelling wave tube
  • Gyrotrons, (2 to > 200GHz)
  • Other uses of Microwave high power amplifiers
    • Radar
    • Nuclear magnetic resonance (NMR)
    • Microwave ovens
    • Induction furnaces
    • Nuclear fusion research (plasma heating)
    • Particle accelerators
    • Plasma discharge devices
    • Weapons (Active Denial System, ADS)

8. Elements of a SSPA -0.5 57 Sortie RF /Output RF WR430 Info PR /R/P Info Info PS /O/P Info Test PS Output power sample Sortie analogique Analog output Dtection ROS VSWR detection Combi- neur 4 voies 4 way combi-ner DNS2030 Divi- seur 4 voies 4 way divider RF switch Entre RF RF input Tlgestion RC&M Tlgestion RC&M Supervision Supervision Cartes gestion /Control boards -4 -2 -2 +44 +28.5 -1 -2 -1 -5 -10 34 32 4x24 4x52.5 dB dBm DNS2030 DNS2180 G 1 dB P 1 dB Minimum Rseau /Mains 240 V 50 / 60 Hz Commu- tateur RF Diviseur 2 voies / Two ways divider DNS2180 DNS2180 DNS2180 Attnuateur variable 0-30dB Variable attenuator Limiteur Limiter 9. Elements of a KPA 10. What a SSPA looks like

  • Old, Si BJT;
  • Now AsGa, LDMOS-Si
  • Coming GaN and SiC
  • Architecture:
    • Driver chain
    • Parallel power stages
    • combiner (Radial, corporate, spatial combiner)

11. SSPA technologies

  • Different materials (Si, AsGa, GaN, SiC, )
  • Different transistors (LDMOS, MESFET, HEMT, )

12. How works a Klystron?

  • Thermoionic device (works around an electron beam)
  • Very high voltages and strong magnetic fields involved

13. What a Klystron Looks Like? 14. Are the klystrons so old?

  • Russell and Sigurd Varian invented the klystron in August 1937 at Stanford University, based on the velocity modulation theory from A.Arsenjewa-Heil and Oskar Heil (wife and husband) (1935) and Hansen workson electrons focusing and acceleration

15. Klystron limits (TH2089)

  • Use in synchrotron applications
  • 1.3 MW CW at 350 MHz
  • 100 kV Beam voltage, 20 A
  • 5 meters long, 2500 kg

16. Klystron limits (TH2100-TH2155)

  • Use in synchrotron applications
  • 45 Mw peak, 20 kW average at 3 GHz
  • 300 kV Beam voltage, 340 A
  • 70 kg, 1.65 meters
  • 80 kg, 1.5 meters

17. Klystron limits (VKX7864A)

  • Interplanetary Radar Applications
  • IEEE MTT Vol 48no 6 June 1992
  • VKX 7864A
  • 250 kW @ 8510 MHz
  • Collector dissipation 4.3 kW/in 2
  • 735 lb
  • 51 kV beam Voltage, 11 A
  • Efficiency 45%
  • Linearity is important

18. SSPA vs. KPA Focus magnet Protections Heater supply Divider + Combiner Ancillary elements High (8kV 200 kV) Low (10 50 V) Supply voltage Single Point Failure Graceful degradation degradation ~ 20.000 hours (Tube exhaustion) > 100.000 hours Reliability > 1 MW (L Band) ~300 W/TRT (L Band) ~ 2 KW amplifier Max. Power (L Band) ~ 100 GHz ~ 20 GHz Max. Frequency 1937 ~ 1980s Origins KPA SSPA 19. ESTRACK Amplifiers

  • S Band (2025-2120 MHz)
    • S-SSPA 500 W
    • S-LPA 2 kW
    • S-HPA 20 KW
  • Ka Band (34200-34700 MHz (future)
    • Ka-KPA 500 W
  • X Band (7145-7235 MHz)
    • X-SSPA 500 W
    • X-LPA 2 kW
    • X-HPA 20 KW

20. COTS for ESA?

  • ESA employs the following bands:
  • S Band (2025-2010 MHz):
    • Also used by commercial operators. Increasing restrictions
    • COTS available up to 500 2kW
    • 20 kW only used by Agencies in Deep Space (no COTS)
  • X Band (7145-7235 MHz)
    • Band only for Agencies use (no commercial operators)
    • No commercial COTS in the market
    • 20 kW only used by Agencies in Deep Space (no COTS)
    • Closer cots are military bands (7.9 to 8.4 GHz)
  • Ka Band (34200-34700 MHz)
    • Same problematic than X Band (only Agencies)
    • Closer cots are Ka Uplink bands (27 31 GHz )
    • Less developed than X Band

21. S-SSPA 500 W

  • DNS 2400
    • Old unit from the 80s
    • Still working in KRU, KIR, PER, VIL
    • Modular
    • Graceful degradation
    • redundant preamplifier
  • DNS 2703
    • Installed in MSP and RED
    • Will be installed in NNO
    • Smaller
    • Cheaper
    • TCP-IP
    • Additional functions (O/P power TM, Log File, ALC, )
    • More reliable (we expect, still not time to verify!!)

22. S-LPA 2 kW

  • Old DNK 2703
    • NNO, KRU and VIL-2
    • Obsolete. No maintainable
    • K3S64D(Only possible COTS)

23. S-HPA 20 KW

  • Needs a DI cooling system
  • 203-S from ETM in NNO
  • Single unit in the network
  • No way to transmit S band 20 kW in other station (regulatory issues)

24. X-SSPA 500 W

  • DNS 7703/500 from SODIELEC
    • Developed end of 90s
    • Modular
    • double preamplifier
    • Graceful degradation

25. X-LPA 2 kW

  • DNK 7703 for NNO and DS3
  • K3C for CPI (COTS) for CEB
  • Former RSI and Vertex units already removed

26. X-HPA 20 kW

  • Needs a DI cooling system
  • ETM 203-X for NNO and CEB
  • RhI TRA 000AA for CEB and DS3

27. De-Ionized Cooling System

  • The cooling system is required to extract 90 kW of heat from a klystron smaller than a bottle of wine.
  • De-ionized and very pure water required to avoid corrosion of the copper body of the tube

28. Ka-KPA 500 W (future)

  • Option for Cebreros and DS3 stations
  • Ka Band uplink required for RS experiments of Bepi Colo

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