European Space Agency

RF Sensing Equipment in Ka Band for Eurostar 3000 Platform


The purpose of the present development was to adapt to the EADS ASTRIUM needs (Eurostar 3000 P/F) the equipment already developed by THALES ALENIA SPACE for their own platform in the frame of previous ESA contracts (in particular contract ref 20141/NL/NH).

The developed RF equipment is dedicated to be used on EUROSTAR 3000 Platform (EADS ASTRIUM) and has to operate with one or several Ka band beacons.

When connected all together, the developed equipment is the constituent for the RF Sensing Subsystem which uses the RF signal transmitted from one or several ground beacons to measure the angular pointing errors of the antennas.

Four types of equipment were developed and qualified in the frame of the present contract:

  • Ka Band Signal Combiners
  • Ka Band Antenna Switch Matrix
  • Ka to C Down Converters
  • C Band Autotrack Receivers

The designs of this equipment were derived from those developed in the frame of ESA ARTES 4 contract 20141/NL/NH (in Ku + Band) and from the developments of Ka Equipment which were performed previously in the frame of ESA DOMINO program (contract nr. 14278 and 14279).

The Signal Combiner and the Antenna Switch Matrix equipment were developed in Ka frequency band (27 – 31 GHz), the Down Converter was developed with an input frequency range in Ka Band (27-31 GHz) and an output frequency range in C Band (5.9 to 6.4 GHz). The Autotrack Receiver has RF interfaces in C band (5.9-6.4 GHz).

The equipment was developed to be compatible with the EADS ASTRIUM EUROSTAR 3000 platform.

Those 4 EQMS were to be delivered (after qualification) to EADS ASTRIUM for inclusion (together with an EM signal combiner) in their test bench for subsystem and system level tests.

Also, a ground equipment named “ Digital Simulator”, which was simulating the Autotrack Receiver digital operation, was manufactured and delivered to EADS ASTRIUM for advanced testing.


Apart from the technical issues linked to the development of each particular unit, the main challenges of the development were the following:
The development contract was conducted in parallel to the Ka SAT satellite contract where flight models had to be delivered to EADS ASTRIUM very close to the dates of qualification of the EQMs.
The equipment was derived from THALES ALENIA SPACE system design. Therefore, EADS ASTRIUM was discovering their particularities and building their own system in parallel of the equipment design activities.


The Project enables THALES ALENIA SPACE to sell the developed equipment to ASTRIUM as well as to other companies using similar interfaces as those of the EADS ASTRIUM EUROSTAR 3000 bus.

The project already found two direct applications: the KaSAT and Yahsat programs.

On the KaSAT Program, the equipment was sold to EADS ASTRIUM who was Satellite Prime Contractor.

On the Yahsat Program, where EADS ASTRIUM and THALES ALENIA SPACE were sharing the position of prime contractor, the equipment was part of THALES ALENIA SPACE activities sharing.


The following synoptic presents the generic architecture for an RF sensing subsystem, which includes the 4 types of equipment which were developed in the frame of the present contract.

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Signal Combiner:

General description:
The Signal Combiner functionality consists in modulating (BPSK) one of the two signals from the RF sensor feed and adding it to the other RF sensor output, thus combining them to a single RF signal. The resulting coherence between signals allows high transmissions lengths inside satellite.

Main specifications

Performance Requirement
Frequency Band 27 to 31 GHz
Operating Bandwidth 12 MHz
Input Power Range of Σ Signal -100 to -50 dBm
Input Power Range of ∆ Signal -150 to -50 dBm
Power consumption < 0.5W
Σ & ∆ Inputs WR28
Output coaxial RF K
TM&TC interface 15P connector
Mass 350g
Size 100*78*43 mm

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Antenna Switch Matrix:

General description
The Antenna Switch Matrix function is to select one antenna beacon signal among N (2<6), and to deliver the selected signal to the Autotrack Receiver. It also distributes voltage supply and modulation signal to the Signal Combiner units (up to 4).

Main specifications:

Performance Requirement
Frequency Band 27 to 31 GHz
Operating Bandwidth 12 MHz
Input Power Range from –120dBm to –65dBm
Gain >24.5 dB
Power consumption <9W
Inputs Up to 6 coaxial K
Output 2 redundant coaxial
Autotrack receiver interface 2 * 15P LF connector
TM&TC interface 1* 25P LF connector
Bus interface 3*15P LF connector
Mass RF part+ LF part: 3806 g
Size RF Part:254*165*80 mm
LF Part:254*175*172 mm

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Ka/C Down Converter:

General description:
The Ka/C Down Converter functionality consists in translating (to C Band) the Ka band signal coming from the Antenna Switch Matrix and sending it to the Autotrack Receiver.


(Features Continued)

Main specifications

Performance Requirement
Input Frequency Band 27 to 31 GHz
Output Frequency Band 5856 MHz +- 6MHz
Operating Bandwidth 12 MHz
Input Power Range -110 to -60 dBm
Power consumption <6.5W
Gain >20 dB
Input interface WR 34
Output SMA -F
Power supply &TM TC 15P connector
Mass 820 g
Size 183*46*153 mm

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C-band Autotrack Receiver:

General description:
The Autotrack Receiver RF input reflects the 2 components (ρ, θ) of the pointing error of the on-board antennas. The Receiver is able to process subsequently from 1 up to 8 antennas. Its main function is to demodulate the pointing error data into accurate ρ, θ values. It also processes the ground beacon identification coding acknowledgement.

After processing, and under request, it directs these RF sensor relative phase and amplitude values to EUROSTAR 3000 Satellite through its specific MIL-STD 1553 serial interface. It drives the Switch Matrix, by sequencing the antennas being received via the individual LNA power supply switching.

It provides the modulation signal to the Signal Combiners, via the Switch Matrix.

Main specifications:

Performance  Requirement
Frequency Band 5856 MHz
Operating Bandwidth 12 MHz
Types of Uplink Waveforms PM/BPSK modulated CW or pure carrier wave
Input Power Range of Σ Signal from –90dBm to –60dBm
Power consumption <23W
Input SMA female connector
TM&TC interface 1* 25P LF connector
Bus interface 1*15P LF connector
Mass 1720 g
Size 229*78*195 mm

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Digital Simulator:

General description:
The Digital Simulator functionalities are as follows:

  • Generate or receive the command signals of antenna de-pointing parameters,
  • Generating through a modulator a signal similar to the one generated by the signal combiners,
  • Demodulating that signal,
  • Calculating the antenna de-pointing parameters,
  • Estimating the performance with regards to the input data.

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Project Plan

The equipment development plans were as follows:

Signal Combiner
Simulations and breadboarding of the RF part;
EQM manufacturing, qualification and delivery to EADS ASTRIUM.

Antenna Switch Matrix
Breadboarding of LNA RF slice, DC/DC converter, TMTC interface; Modification of distribution and protection board schemes;
EQM manufacturing and qualification and delivery to EADS ASTRIUM.

Down Converter
Partial breadboarding and testing of DC/DC converter and RF modules; EQM manufacturing and qualification and delivery to EADS ASTRIUM.

Autotrack Receiver
Design and breadboarding of 1553 interface board, DC/DC converter; Modification of mechanical housing; EQM manufacturing and qualification and delivery to EADS ASTRIUM.

Digital Simulator
Use of EUROSTAR 3000 Autotrack Receiver low frequency and of Spacebus 4000 Digital Simulator;
Delivery to EADS ASTRIUM.

Current status

The four RF equipment have been qualified successfully.

They were delivered to EADS ASTRIUM at their full satisfaction, as well as the Digital Simulator.

The KaSAT satellite equipment was also delivered to EADS ASTRIUM.
The Satellite is to be launched end of year 2010.

EADS ASTRIUM and THALES ALENIA SPACE already initiated meetings with the purpose of defining which modifications / improvements could be performed on the equipment for next generation.

Status date

Thursday, December 2, 2010 - 14:46