| Customer: ESA/ESTEC (2003 – 2006) | |
 | The main objective of this activity was the development of antenna reflector technologies for the high accuracy and stability required by the operation in Q and V bands including a qualification model for thermal-vacuum tests, thermal distortion tests and RF tests in a Compact Range. |
The Performance key characteristics were:
- Q/V-band
- mass <3kg
- diameter =1.2m
- F/D =1.5
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Within a timescale of about a decade, it is expected that Ku and Ka frequency bands occupancy will increase in such a way to gradually force the migration of satellite telecommunications towards Q and V bands. Propagation losses are more severe at these higher frequencies, also technologies for the ground and space segments are less mature.
Most applications making use of Q/V bands are foreseen to deal with point-to-point communications, covering several scenarios. Among others, proposed applications are:
- Gateway link by the use of Q/V bands, this is a good solution to provide more frequency bandwidth to user links in Ka band.
- Antenna for inter-orbit links may be considered to allow high telemetry data rates from LEO Earth observation spacecraft to GEO satellites.
A preliminary antenna configuration has been proposed in the initial tasks of the study, depending on mission and scenario selection.
Then, structure type, i.e., whether ultra-light membrane or thin shell or even thick shell, should be analysed and tested. Within this initial trade-off, modelling techniques had been of major concern, including thermal and thermo-elastic modelling and their interface. Also testing techniques should be carefully reviewed and questioned.
In a second trade-off stage, relevant parameters should be analysed in terms of optimisation and sensitivity. Of particular interest should be structural properties such as thickness, stiffness and lay-up angles, as well as their imperfections. This sensitivity analyses should take into account the variability of material properties and processes in a stochastic manner, in order to assess robustness of design in a real environment and realistic manufacturing conditions. As an outcome of this sensitivity study, a major conclusion could be the need for implementation of a higher automation in manufacturing procedures.
The mentioned objectives are accompanied by the technological trends concerning mass reduction and wider temperature limits. Firstly, mass reduction should be achieved employing ultra-light concepts, e.g., membrane or thin-sandwich shells supported by highly stable, load-bearing backing structures. Secondly, a higher temperature range withstood by the materials would be a natural and ideal means of thermal control. Hence, implication of new materials and structural configurations are strongly recommended, while preserving radio-electric functionalities In general, analytical predictions are a demanding task when considering the high-accuracy requirements of Q/V bands. In particular, modelling techniques and the conventional hypotheses will deserve special attention and a careful review. Adverse non-uniformity of temperature distribution, transverse gradients and distortions of the shell, thermo-elastic buckling between stiffeners, should be thoroughly analysed. In addition, the high modal density in dynamic response and the non-linearities of thin-shell structures, especially in the presence of pre-tensioning, may also be considered. Trade-off and parameter influence studies dealing with structural configuration and materials have been the backbone of this study.
This objective of the study should be achieved by means of a demonstrator model in terms of thermal and thermo-elastic performances, based on a mechanically representative design. Due to the high demand on shape determination accuracy, appropriate measurement techniques should be employed. Verification procedures should provide measurement uncertainty assessments, as well as a reliable sensitivity analysis and their matching.
Publications:
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Statement of Work:
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