To study and prove by analysis the feasibility of antenna pattern control by ad-hoc modulation of the reflector surface-impedance, inlucluding the reduction of the lower bound on the F/D parameter for good scanning and polarisation purity. Beam shaping is one of the most demanding antenna features required by virtually all applications. The novel concept of pattern control by impedance surface modulation is likely to offer a very effective alternative to existing solutions with the potential of reducing complexity and costs. The concept is of interest for a wide range of purposes, including reflector antenna feeds (to avoid or complement shaping), array elements (to control the element pattern) as well as avionics antennas.
Recent developments have lead to the availability of a modelling technique allowing the efficient design of radiating structures offering a high degree of flexibility in the dynamic surfaceimpedance, i.e. the impedance seen by electromagnetic waves interacting with the structure. The main tool for its control is the modulation of the (artificial) equivalent dielectric constant of the surface, which can be achieved in various ways, e.g. by using multi-layer printed structures with variable shapes or thickness. For instance, the intrinsic limitation of a higlhy conducting reflector surface can be bypassed by moving away from the “perfect mirror” behaviour without compromising reflectivity in an energy balancesense, by modulating the surface characteristics in such a way to obtain a (local) modification of the Snell law. The activity Involves the assessment of candidate applications and the initial study of the most promising one with the demonstration of feasibility by analysis on a set of application scenarii (different coverage requirements, linear and circular polarisation) as well as the devlopments of the tools required to layout the antenna surface and optimise its design. Performance demonstration shall be handled at sample level.
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