Among the identified Imaging antenna architectures potentially suitable to support TX/RX satellite multibeam applications in Ka-band, the Imaging Antenna with Conformal Array and Axes Tilt has been selected at the end of the specific trade-off activity as antenna baseline configuration and designed more in detail for both the operative mission scenarios, i.e. Continental and National.
The Confocal imaging system antenna architecture with Conformal Feed Array is an imaging setup derived from the classic Confocal architecture by optimizing the position and the shape of the non-planar feed array. It is based on an ESA patent design approach.
The optimization process relies on a GO-based caustic region analysis and feed element positions are chosen such to have a planar caustic region surface on the main reflector plane after dual reflection of rays.
The advantage of this configuration is that the produced spot beams guarantee an improved stability in terms of HPBWs, while keeping unchanged the reflector’s geometry and not adding up complexity to the system.
As the major drawback of the selected imaging antenna configuration is the inter-element blockage of feed elements within the conformal feeding array, this aspect has been addresses in detail with the manufacturing and testing of the Critical Breadboard.
The selected Critical Breadboard for the present project consists of 19 identical horns working in Tx Ka band assembled in three different array configurations, one planar and two conformal (on parabolic surfaces).
The RF test campaign (S-parameters and radiated) carried out by Space Engineering on the Imaging Critical Breadboard antennas showed good performances in terms of both Return Loss and Co and Cross-polar radiation patterns, with very good agreement with predicted performances.