Very Large Stable Membrane Antenna Architectures - Report 1 - Research Year 2007

This report provides an overview on the current state of work on ESA Contract No. 20407/07/NL/EM with the title “Very Large Stable Membrane Antenna Architectures”. The work was done at the DLR Institute of Composite Structures and Adaptive Systems in Brunswick and covers the first of three research years. The motivation for this research topic bases on the demand on large, lightweight antenna structures for space-born radar remote sensing applications. The most current used radar an-tennas are designed as deployable structures. Therefore, they were packed on ground before launch, and ones reached their destined orbit, they deploy in any way to their full size. The common deployment concepts are mainly oriented to pantographic mechanisms or unfolding of tile like elements by the use of hinges. Past studies on inflatable antennas and deployable solar sail had shown the potential of novel deployment mechanisms. In contrast to the conventional techniques, these ones don’t deal with connection or reorientation of rigid element. They create a stiff structure out of a slack reeled or folded material that cures after deployment or snap in to a stable state (see carpenter tape principle). From this behavior, objectives like high packaging efficiency and low overall mass arise. To further increase these key parameters, the advancement of deployable structure don’t stop at the means of the antennas backbone structures. It can be continued to the antenna surface as well. Current radar antennas surfaces are manufactured of composite materials by use of car-bon fibers and honeycomb layers. They provide a very good shape accuracy and, compared to non-space applications, could be specified as lightweight structures. Since the designed struc-ture should be used in space, there is still room for improving the antenna surface. Therefore, the approach of using flat, tensioned membranes as substrate for antenna elements, is an im-portant task of this study. As the topic for the first year is defined as “Requirements and Preliminary Assessments“, the document includes literature reviews, interview summaries and first assessments on mission and structure design. In parallel investigations on simulation and measurement of thin ten-sioned membranes has been done