ARTES-5.1 – ESA Telecom Technology Workplan ... - Emits - ESA

Annex 2Page 33Ref. Activity Title Procurement Policy Budget(KEUR)5B.066(09.153.09)Objective:Description:Planned TenderIssueActive Multibeam Sparse Array Demonstrator Open Competitive Tender Type: C 750 3Q 2009 24Estimated Duration(months)The objective of this activity is to design a Ka-band Active Multibeam Sparse Array Antenna considering satellite interfaces and accommodation constraints and to validate the RFperformances by a demonstrator model.Active Direct Radiating Arrays allow generating multiple beams for broadband satellite communication systems with a high degree of reconfigurability and flexibility. They have been rarelyimplemented because of their complexity and cost. These drawbacks are due to the high number of active and radiating elements, and to the poor efficiency of the HPAs (also associated totapering). Active Sparse Arrays with equal amplitude distribution represent a valid alternative to periodic arrays. They offer the advantage of minimizing complexity and cost of the entireantenna system. In fact, a periodic arrays may generate an equivalent tapering by changing the elements positions and allow:- to reduce the number of elements;- to realise phased arrays with a simplified BFN (no amplitude control);- to increase the DC to RF efficiency of active antennas.These major advantages, combined with recent improvements in RF HPAs, may enable drastic improvements in multibeam active arrays.Description of the activity:- pre-design of the Direct Radiating Array including RF, themomechanical and integration aspects.- trade-off on the architectures and technologies reducing power dissipation and mass.- definition of possibly self standing thermal control with dedicated North/South radiators to ease array integration.- establishment of satellite accommodation on earth deck minimising I/F between platform and DRA.- optimisation of the sparse DRA architecture and the performance including: gain/EIRP, isolation, mutual coupling, intermodulation, DC-to-RF conversion efficiency, considering thestate of the art transmit active modules in solid state or Mini-TWTAs.- identification of the required technology improvements and extrapolation of the full antenna performances. Concerning the implementation of the transmit active modules the followingoptions shall be traded-off:- Solid state technology. Emphasis shall be given to wide bandgap semiconductor materials (e.g. GaN) that have been identified as key disruptive technologies for SSPAperformance improvements (RF power, efficiency, thermal properties). Attention shall be given to the thermal properties that will allow increasing baseplate temperatures withsimplified thermal control. The reliability is important as well.- Mini-TWTAs technology Low saturation power TWTs with high efficiency, low dissipated power, small size and footprint, would allow direct connection of TWTs to radiatingelements.- Design, manufacture and test a demonstrator representative of a full antenna aperture. Regarding the active devices, from input beam ports to radiating elements, the use oflaboratory equipments might be considered provided that array performances over the angular domain and frequency range can be validated by tests.Preparation of a cost estimate and comparison of cost with existing designs.