Active array of Quasi optical beamformers – RAFQO 2016

Thales Alenia Space (TAS-F) and IETR developed a unique know-how at the best international level on quasi-optical beamformers (FF-QO), by initiating their collaboration in the ASTRID project GRAIK. A bidirectional pillbox beamformer in Substrate Integrated Waveguide (SIW) technology was designed and validated. It was the object of a patent registration common to both partners (TAS-F and IETR). This beamformer was associated with an active phased array, and with a magnifying optical system based on two reflectors to increase the radiating aperture. In this project, antenna architectures were proposed based on these FF-QO for civil and military missions. In the civil mission, a 2D coverage of 400 beams of 0,18 ° was synthesized. In the military mission, a multibeam antenna, with a 13 dB/K G/T was studied.
These FF-QO were the purpose of an intense attention. They also demonstrated their capacity to work on a very wide bandwidth (Ka Rx/Tx band), and to be coupled with continuous radiating apertures. The beams can thus be formed on a very wide angular sector, without the problem of grating lobes.
These interesting properties were further investigated by TAS-F, IETR and Moulange Industriel de Perseigne (MIP) after the end of GRAIK, in a context of emergence of systems of satellite constellations in Ka band, requiring antennas with large number of beams and antennas terminals with wide scanning capabilities. Two FF-QO have been designed, manufactured and validated. They lead to three projects of patents common to TAS-F and IETR. Additional building blocks were identified, which must be developed: polarizer, Filters Rx/Tx integrated in the accesses.
In the meantime, THALES COMMUNICATIONS & SECURITY (TCS), in the frame of advance studies (PEA), investigated and manufactured active antenna in Rx/Tx for Satcom military and civil terminals. Active radiating panels were manufactured with segregated (KALB) or combined (ARTEMIS) Rx/Tx functionalities for an easier integration on aeronautical of terrestrial platforms.
The antenna concepts developed during GRAIK, compatible with a 2D-electronic operation, are of interest to get rid of one mechanical pointing mechanism.
Today, we are capable of associating these various inventions to propose a concept of active antenna operating in Rx/Tx, realizing a large number of beams over a wide angular sector.
Moreover the proposed architecture is economic as the electronic beamformer is realized only along one axis. Thus it brings the feature of reconfiguration while reducing the material complexity. On the other axis, the beams are realized by the FF-QO, operating in Rx/Tx. Aimed applications are the ones of the GRAIK project, and also the satellite and terminal antennas for satellite constellations, as well as the terminal antennas on theatres of operation.
This Maturation project also addresses appropriate manufacturing technologies, plastic injection molding for the FF-QO and SIW for the electronic beamformer.
As a matter of fact, both ground terminals and large satellite constellation, require a very large number of antennas. Achieving low cost is essential. The plastics processing industry considerably evolved. The preliminary evaluations with MIP confirmed that the plastic injection molding is relevant for the concepts of FF-QO. The manufacturing constraints will be injected in the RF design.
For the electronic beamformer associated with the active antenna, the GRAIK project demonstrated the relevance of the SIW technology.

An active antenna architectures, working in Tx/Rx, and of reduced complexity, was designed at the end of the GRAIK project. Feasibility of the various equipment constituting this antenna was established. RAFQO 2016 objective is to develop complementary building blocks, to integrate them into the existing designs, and to manufacture them at low cost thanks to the plastic injection molding technology. A final demonstrator will validate the proposed concepts.