After an initial survey of the state of the art about the deployable antennas for ground application and the definition of the antenna requirements, a pre-selection of 10 different antenna concepts was performed. Then a trade-off study involving all the team was used to select the three best candidates, which were developed up to the preliminary design status.
Some samples for the reflective surface materials have been manufactured. The results of the mechanical and RF tests performed on the samples were used to finally select the best candidate for the project, the “umbrella” concept with a CFRS reflective surface.
The detailed design and the following manufacturing activities of the antenna have been successfully completed.
The first RF measurements have shown that the accuracy of the first reflective surface was not enough to guarantee the compliance with all the antenna requirements. The root causes for the inaccuracy have been identified in the hinges of the ribs and in the manufacturing process of the CFRS surface. The following corrective measures have been adopted:
- Update of the design and manufacturing of new hinges. The new hinges are now provided of preloaded angular contact bearings and of a new end-stop. The new design provides a much better accuracy and repeatability of the final position of the ribs.
- Manufacturing and assembly of a new reflective surface. This activity have been contracted to Large Space Structures UG, a German company having specific heritage on design, analysis and manufacturing of CFRS antenna reflectors for space applications.
Figure 1: Photogrammetry measurement set-up of the URDA antenna with the new RF reflective surface installed (from Large Space Structures UG)
The following testing phase includes RF characterization in the anechoic chamber and the field test in operative conditions to establish a link with a satellite and make receive/transmit activities.
The end of the activities is scheduled for December 2015.