Antenna Structures

Highly Stable Antenna Structures

The main concern related to functional performances considering the demanding in-orbit environment and the test conditions on ground is the thermo-elastic stability. Thermo-elastic analyses are performed in TEC-MSS employing NASTRAN for linear thermoelasticity and ABAQUS for non-linear cases. The thermal inputs delivered by thermal analyses are converted into nodal or element loads either with specific FEM tools within PATRAN or devoted tools such as SINAS.
In-house developed tools are used to calculate RMS distortions and depointing after best-fitting to the reference paraboloid or other shaped surface. Parametric studies are performed in order to characterise sensitivities to parameters, as shown in figures 1 and 2 for classical hot and gradient thermal cases (e.g. reproducing transition into eclipse in GEO).
Thermoelastic distortions of parabolic reflector in hot case and gradient thermal cases [R1].
Sensitivity of peak thermal distortion to core thickness for given uniform temperature and gradient cases [R1].
These parametric studies can also be implemented using Monte Carlo simulation as was performed during the Tiger Team for the Herschel telescope. In this case the focal length sensitivity to material properties (SiC and Invar) was studied in the stochastic sense, obtaining clear correlations. The core analytical procedure is shown in Fig. 3 and the typical output obtained with ST-ORM is shown in Fig. 4, providing clear evidence of parameter correlations.
Fig. 3. Flow of Data and Analysis Tools
Fig. 3. Flow of Data and Analysis Tools
Stochastic simulation
Fig 4. Stochastic simulation
The activities of the structures Section in highly stable antenna structures also include technology development within the TRP and ARTES programmes. In particular the materials and processes employed for Ka band and Q/V band antennas developed within these contracts are used in flight programmes such as Ka-Sat. These include development of new Carbon Fibre Reinforced Plastic constructions for high temperature and low thermal expansion, qualification of pitch Carbon fibres and low temperature curing resins for reflecting surfaces, non-specular sun shields.
Fig. 5. Ka-Sat 2.6 m Ka band reflector
Fig. 5. Ka-Sat 2.6 m Ka band reflector
Fig. 6. STANT Gregorian multibeam antenna
STANT Gregorian multibeam antenna
Last update: 11 March 2013

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