Investigation of Compact and Multi Band Waveguide Array Antennas for Space Applications

Topic: Non-Terrestrial Networks (NTN) are strongly encouraged for the next generation of high connectivity solutions in 2030, notably through the IRIS² initiative, the new European Satellite constellation. Such multi-orbital links will open new paradigms for worldwide infrastructures offering enhanced data bit rates with controlled energy consumption and environmental impact. Great challenges appear therefore on such multi-link connectivity, exploiting simultaneous multi-band multi-beam links. The designs of reconfigurable miniaturized antenna modules are consequently expected to propose disruptive technologies and concepts for highly integrated solutions to high-performance micro-satellites. The solutions should be adaptable for telemetry systems in the high-data rate, low-earth orbit (LEO) satellites (S to Ka bands) used for atmospheric sensing (Carb-Chaser, MERLIN, MicroCarb etc.).

Scientific goals: Multi-band antennas especially those working in two operating bands are suitable for satellite systems utilizing unique uplink and downlink frequencies for improved terrestrial connectivity. The antennas must be compact, directive, less lossy and be capable of handling high power. An all-metal slotted waveguide array (SWA) antenna meeting these requirements possess significant challenges abiding by the polarization requirements, mutual coupling and fabrication design rules.

Innovative nature: We propose to develop new configurations of multi-band mono-access-port antennas supporting wideband and multi-polarization modes. The innovation will primarily be on the technique to modify waveguide fields suitable for multi-band radiation with desired polarization and minimum excitation ports. These modifications demand unique modeling of waveguide fields by geometric profiling of the guiding structure, or by innovative perturbation of the geometries inside the waveguide. Single port SWA antenna capable of radiating two or more frequencies using a simple and compact antenna architecture will be investigated by employing ridges or conformal geometric modifications, which appear feasible through advanced additive manufacturing (3D printing) processes.

Positioning in relation to the state of the art: Dual band SWA [1] antenna solutions use complicated feeding networks [2, 3, 4], usually radiating in different directions that are imperfectly controlled [5, 6] with great bottlenecks, of managing single or multiple feeding waveguides [7, 8, 9], simultaneously. The latest solution in the state-of-the-art [9] offers single polarization for both bands and employs a wide waveguide affecting the side-lobe performance. This project will focus on the limitation of mutual coupling and side-lobe levels of these antennas and will extend the dual-band solution into the multi-band regime. Polarization diversity will also be considered.

Proposed approach: We propose to investigate on the design of innovative, highly integrated multi-band, multi-polarization antenna structures for up-down satellite links in the S-Ku-Ka bands. We will focus on the limitation of mutual coupling and side-lobe levels, and will extend the dual-band solutions into the multi-band regime, considering the polarization diversity. New waveguide structures supporting single or multiple modes will be studied, exploiting 3D ridges with geometrical patterning. Positioning of the radiating slots considering mutual coupling, sidelobe level and fabrication tolerances will also be studied. Analytical studies, numerical modeling and prototyping for experimental validation will be considered for peer reviewed publications.

Expected results
1.    Technological prototypes (dual/multiple band single radiating waveguide with different polarizations, Ridge based compact solutions for dual/multiple bands, Conformal ridge-based geometry to improve mutual coupling between radiating slots)
2.    Disseminations in international conferences (IEEE APs, IMS) and focused workshops (with ESA & CNES) 
3.    PhD manuscript and thesis defence

Future prospects: The solutions are integrable for space applications but can be considered for millimeter wave and sub-THz communications such as in vehicular sensing systems. The ridges or the radiation slots can be replaced with frequency sensitive geometries inspired by the idea of metasurfaces.