European Space Agency

Modular Top Floor Antenna - Phase II


The main objective is to obtain a robust design concept for the main structure of the Top Floor. This concept is adequate to support different antenna lay-out (in terms of antenna number or configurations) with minimum modifications.

The robustness of this design should be reached at the same time as others important objectives:

  • Optimized mass: Assumed an antenna arrangement of two fixed 1.1m Gregorian plus one steerable 1.0m Single offset antenna, the total mass of the structure is limited to 45 Kg
  • Stiffness: First mode higher than 35 Hz
  • Strength: The structural design shall be able to withstand an envelope of the maximum environments specified by the most relevant primes.





The most remarkable benefits of the current design are highlighted below:

Modular concept adaptable with minimum changes to different configurations.

Possibility to board several missions in a common structure with a single qualification process.

MTF design can be considered as an extension of the payload module increasing the earth deck capability.

ITAR free design.

Easy assembly process with the corresponding cost and time savings.

Good mechanical performances with low mass.

Generation of an industrial dossier to be used systematically for all the products as basic design dossier.


The Modular Top Floor Antenna Assembly provides a common support for an increasing number of antennas (including reflectors, feeders and sub-reflectors).

This design is an important step forward on the ECE Top Floor Antennas experience, evolving from a mission specific design to a modular concept which employs standardisable building blocks.

The lower interface consists on a metallic ring easily adaptable to different interface requirements.

The geometries of the lower and upper masts provide a generic interface for RF components as well as the necessary robustness of the structure.

The solution adopted for the main platform support ensures a high versatility of the design, a good strength/mass ratio and a very stable TED behaviour.


The main supporting structure is made by the following sub-assemblies:

Interface ring and raising cylinder

Intermediate platform


Upper mast

Feed chain supports

Upper platform for sub-reflector support


The full development was split in two phases:

  • Phase I: Dedicated to fix the requirement and to obtain a preliminary analysis and design as well as to manufacture a demonstrator of the lower part of the structure. The phase I activities are developed in the frame of the ARTES 5.2 programme.
  • Phase II: To drive the preliminary design to a detailed design and to manufacture and Qualification Model. This phase was presented in the frame of the ARTES 3.4 programme.


This development program has some interesting and challenging aspects:

Mitigate risks in TFAA structure when steerable reflector (load in cantilever).

To obtain a stable design in front thermal loads to provide good TED performances of the antennas.

To find an innovative design able to be adapted to several configurations through non dramatic changes in the structure.

Current status

Modular Top Floor development program has been closed on March 17, 2015.

Proposed design has been successfully submitted to a complete qualification test campaign.

This improved Top Floor Antenna concept is, therefore, ready to be used in commercial applications.

Status date

Tuesday, March 21, 2017 - 11:08