We propose a new architecture for array antennas able to achieve a high-gain performance by using a low number of elements and uniform-amplitude excitations. The solution is realized through a fast and deterministic design technique able to accurately emulate, by exploiting only the feeds' size as degree of freedom of the synthesis, 'ideal' continuous aperture sources fulfilling at best the assigned directivity requirements. The given theory is supported by numerical examples concerning the synthesis of isophoric direct radiating arrays devoted to a multibeam coverage of Europe from a geostationary satellite.

Abstract-By taking inspiration from [1], a synthesis strategy is proposed for the case of planar arrays and ring shaped patterns which does not require the exploitation of global optimization procedures. In particular, the approach is able to determine a priori (that is, without solving the overall design problem) whether the given power pattern design constraints can be fulfilled or not, and, in the adfirmative case, to determine the needed excitation coefficients in a fast deterministic manner. Although the approach does not apply to generic planar arrays and generic constraints, it applies to a large number of problems of actual interest, and outperforms some recently published synthesis procedures. Moreover, it may serve both as a reference solution for more general synthesis procedures, and as an elementary brick for more cumbersome synthesis problems.

Abstract-In this paper, we describe a new full-wave integral equation model to tackle electromagnetic scattering problems arising from objects buried in layered media. Such a model is a rewriting of the usually adopted Contrast Source integral equation and is named Contrast Source-Extended Born (CS-EB) owing to this circumstance and to the relationship existing among its linearization and the Extended Born approximation. By means of this alternative formulation, it is possible to modify the relationship among the scatterer permittivity and the field it scatters, thus possibly reducing the degree of non-linearity of this latter relationship. Accordingly, in these cases, the adoption of the CS-EB model may be convenient with respect to traditional ones in both forward and inverse scattering problems.

Abstract-The problem of field focusing onto a target location in an unknown scenario is considered. In particular, we devise an adaptive procedure in which first an image of the unknown region where the target point is located is formed via the linear sampling method (LSM). Then, the LSM result is used also to define the excitations coefficients for the array elements needed to focus the field. This novel approach to focusing is described and tested with numerical examples.

With reference to the mask-constrained power synthesis of shaped beams through fixedgeometry antenna arrays, we elaborate a recently proposed approach and introduce an innovative effective technique. In particular, the proposed formulation, which can take into account mutual coupling and mounting platform effects, relies on a nested optimization where the external global optimization acts on the field's phase shifts over a minimal number of 'control points' located into the target region whereas the internal optimization acts instead on excitations. As the internal optimization of the ripple is shown to result in a Convex Programming problem and the external optimization deals with a reduced number of unknowns, a full control of the shaped beam's ripple and sidelobe level is achieved even in the case of arrays having a large size and aimed at generating large-footprint patterns. Examples involving comparisons with benchmark approaches as well as full-wave simulated realistic antennas are provided.