PhD THESIS PHASED ARRAY ANTENNAS WITH SIGNIFICANT REDUCTION OF AMPLITUDE/PHASE CONTROLS • Laboratories o Institut d'Électronique et de Télécommunications de Rennes (IETR), UMR CNRS 6164. Rennes, France. www.ietr.fr Département ‘Antennes et Dispositifs Hyperfréquences’ – Equipe ‘Systèmes Rayonnants Complexes’, o Antenna and Sub-Millimetre Wave Section, ESTEC/ESA - Office Da207, Keplerlaan 1, PO 299, 2200 AG, Noordwijk, The Netherlands. • Doctoral school: MATISSE (http://matisse.univ-rennes1.fr/) • Keywords Phased arrays, Multi-beam antennas, leaky-wave antennas, Fabry-Perot cavities. • Context and overview of the problem Phased array antennas are of great interest for applications requiring flexibility (coverage reconfiguration, electrical beam scanning). Still, their use in space applications, either as ground terminals or on board of a satellite, is often limited by the large size of the required antenna aperture, resulting in a large number of single array elements. Techniques, including thinned and sparse arrays, have been widely investigated as a mean to reduce the number of array elements and/or amplitude/phase controls, thus reducing the overall antenna complexity while maintaining acceptable side-lobes and grating-lobes levels. But these solutions usually suffer from reduced antenna aperture efficiency. As a consequence, for a given directivity requirement, thinned or sparse arrays often need larger antenna apertures in terms of physical dimensions. An attractive solution to overcome this limitation consists in combining a thinned array antenna with a superstrate layer (Fabry-Perot cavity) as a mean to introduce beam scanning capability while reducing the number of controls. An alternative design, which could serve as a benchmark, is the concept of overlapped subarrays. In this antenna concept, an amplitude/phase control is used per sub-array. The sub-arrays are overlapped at beam forming network level to mitigate grating lobes. • Main goals The PhD project addresses three major goals: ⇒ To investigate configurations using either thinned or sparse arrays combined with regular or irregular superstrate layers to significantly reduce the array antenna complexity and number of controls while maintaining high aperture efficiency. ⇒ To investigate combined antenna configurations where the available space in a thinned array is used to interleave another antenna, a possible application being a combined transmit/receive phased array antenna for user terminal applications. ⇒ To prototype and validate experimentally the numerical results. • Brief description of the work The work of the PhD candidate will focus on: (1) Accurate analysis of phased array/multi-beam solutions based on surperstrate configurations. A comparative analysis with other solutions used for multi-beam applications will be also performed. The study will identify the needs and current limitations of antenna solutions for space applications. (2) Formulation and development of an electromagnetic tool based on a Green’s function formulation for the analysis of superstrate configuration. The tool will allow a fast analysis of superstrate configurations for multi-beam applications. Bandwidth, efficiency, dispersion analysis will be taken into account by the tool. The tool will be aimed to array configurations. (3) Experimental validation of the electromagnetic and efficiency tools with several prototypes. The prototypes will be manufactured and tested at IETR/ESA. • Main expected results o Comparative analysis of current solutions for multi-beam applications, o Electromagnetic tool for the analysis and design of superstrate-based array structures, o Antenna configuration fulfilling the requirement for multi-beam solutions for space applications, o Prototyping and experimental validation of several analyzed structure. • International cooperation The present PhD project is in cooperation with the European Space Agency (ESA). • Location and supervision The PhD project will be mainly developed at the IETR, Rennes. Part of the PhD will be spent at the ESA, The Netherlands. The supervisors of the PhD student will be Mauro ETTORRE, IETR, CR2 CNRS (firstname.lastname@example.org), Ronan SAULEAU, IETR, Professor (Ronan.Sauleau@univ-rennes1.fr), and Dr. Nelson FONSECA, Antenna and Sub-Millimetre Wave Section, ESTEC/ESA, The Netherlands (email@example.com). • Candidate profile The PhD candidate should hold a Master degree M2R in electrical engineering, physics or an equivalent title recognized by the doctoral school MATISSE. In particular, he should master electromagnetic theory, physics, mathematics, and circuit analysis. A good level of spoken and written English is required. • Application Interested candidate should send a detailed CV and motivation letter by email to Mauro ETTORRE (firstname.lastname@example.org).