30, June 2022

ESA Open Invitation to Tender: 1-11415
Open Date: 28/06/2022 14:53 CEST
Closing Date: 06/09/2022 13:00 CEST

Future GEO Very High Throughput Satellites require antennas larger than 3-4 meters for Broadband applications. The accommodation of these antennas on board GEO satellites is a great challenge. Having 2 reflectors instead of 4, still keeping a simple single feed per beam excitation scheme, can represent a significant improvement. The most mature antenna for multibeam applications adopts a Single Feed per Beam concept and 3 or 4 main reflector apertures. It is needed to develop an antenna system based on only 2 metallic diffractive gratings instead of 3 or 4.Superimposing to conventional metallic reflectors an ondulated periodic profile with a periodicity in the order of the central wavelength will excite one or two grating lobes in addition to the specular reflection mode. These types of corrugated screens are well known in Optics – see Blazed and Bragg diffraction gratings. Simulations carried out show that, by properly defining the ondulated profile, it is possible to reflect 95% energy in the first grating lobe while minimising the energy associated to the specularly reflected wave. As a consequence, the beam deviation factor in a multibeam antenna can be reduced by a factor close to 2. In order to compensate for the frequency scanning of the first grating lobe, the reflection on a second diffractive grating can be introduced. This dual reflector grating system has been preliminarily validated.The activity is dedicated to the optimization of diffraction gratings for multibeam applications. It aims at minimizing of the total equivalent beam deviation factor while maintaining a frequency bandwidth compatible with High Throughput Satellite Systems (i.e. about 10%).This activity encompasses the following tasks:- metallic gratings for bidimensional antennas and plane/spherical wave excitation;- three dimensional antenna reflectors characterised by double curvatures;- extension to dual reflector two- and three-dimensional optics in order to compensate the frequency scanning of the first grating lobe;- identification of the most promising configuration for a detailed optimization, analysis and design;- breadboard in order to prove the effectiveness of the concept;- antenna trade-off and follow-on activities

Directorate: Directorate of Tech, Eng. Quality
Estabilishment: ESTEC
ECOS Required: No
Classified: No
Price Range: 200-500 KEURO
Authorised Contact Person: Anze Singer
Initiating Service: TEC-EFA
IP Measure: N/A
Prog. Reference: E/0901-01 – Technology Developme
Tender Type: Open Competition
Technology Keywords: 7-A-II-Reflector and Lens Antennas
Products Keywords: 2-L-1.1-b-Antenna Towers and/or Reflectors

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