Cooled Low Noise Amplifier Implementation on Large Platforms

Status date

The objective of this predevelopment activity is:

  • To define the best cooled LNA thermal control design and accommodation for Alphabus,
  • To identify the critical thermal control components,
  • To provide to the system the impacts of the G/T improvement on the thermal control mass and heater budgets allowing then for the selection of the best compromise at system level.

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Focus is given on passive thermal control devices but the active cooling means will also be investigated.


Alphabus missions include payloads with very stringent G/T requirements. Considering the antenna gain and noise temperature, one way to comply with this requirement is to minimise the input section temperature by:

  • Accommodating the LNAs as close as possible to the Rx antenna feeds in order to minimise the input losses,
  • Cooling the LNAs in order to decrease their Noise Figure.

The expected benefits from this study are to provide to the Alphabus programme:

  • Thermal Constrol System inputs in order to assess the real benefit of cooled LNAs at system level,
  • The minimum LNA temperatures achievable with simple and cost-effective passive thermal control technologies,
  • An optimised and generic cooled LNA design which could afterwards be tuned to the LNA quantity baselined for each specific Alphabus mission*.

* Cooled LNAs have been identified as necessary for several Alphabus missions involving Ka-band payloads oriented towards broadband multimedia applications (coverage sampled with users spots and gateways).




The tasks performed under the project are organised as follows:

  • Task 1 - Cooled LNA thermal control state-of-the-art
  • Task 2 - System performance versus cooled LNA temperature
  • Task 3 - Passive and active thermal control concept for cooled LNA
  • Task 4 - LNA accommodation on Alphabus & justification
  • Task 5 - LNA thermal control component specification
Current status

The general passive and active concepts have been established and the trade-off between them is finalised. Several concepts have been studied for the passive solution with several sun-shield shapes. The selected solution will be further studied in detail for two different payload configurations.

Next Steps:

  1. Accommodation of LNA unit and associated thermal control on Alphabus platform for one conservative payload mission,
  2. Thermal performances to be assessed for this mission,
  3. Issue of component specification.