O. M. Bucci

A DETERMINISTIC APPROACH TO THE SYNTHESIS OF PENCIL BEAMS THROUGH PLANAR THINNED ARRAYS

This paper presents a simple and innovative deterministic approach to the synthesis of uniformly excited thinned arrays able to fulflll constraints concerning both the sidelobe level and the value of the radiated far fleld (and/or of the directivity) in a set of given directions. Starting from a reference regular (periodic or even aperiodic) lattice and from an optimal continuous reference source fulfllling at best the required speciflcations, the proposed approach flnds out both the number and the location of the isophoric (i.e., equi-amplitude) radiating elements to withdraw in a fast and efiective fashion. In fact, it is based on a deterministic best-fltting procedure which takes inspiration from existing density taper techniques. Examples are provided with reference to the synthesis of large circular arrays and conflrm the interest of the proposed procedure.

On the optimal synthesis of shaped beam sparse arrays having uniform amplitude excitations

By exploiting not widely diffused results in the synthesis of shaped beams by means of fixed geometry linear arrays, as well as recent results in the synthesis of pencil beams by means of sparse arrays, we set a frame for a deterministic and hence fast synthesis of shaped beams through sparse arrays having an uniform amplitude. Preliminary results, supporting the effectiveness of the proposed strategies, are also presented.

2D inverse scattering: degree of nonlinearity, solution strategies, and polarization effects

Quantifying the degree of non linearity with respect to the permittivity profile represents in interesting possibility for quantifying the difficulty of both forward and inverse scattering problems. With reference to the 2D case, in this paper new tools are proposed that allow to determine the degree of non linearity while changing maximum value, dimensions and spatial frequency content of the unknown permittivity profile, as well as polarization of the incident field. As such, the proposed tools allow to identify new solution strategy for the inverse problem and the simpler nature of the TE (vectorial) problem. Numerical examples support the conclusion.

Some recent advances in the synthesis of isophoric sparse arrays for satellite communications

This paper discusses some recent advances in the synthesis of isophoric sparse arrays, with reference to satellite communications. In particular, we first summarize some of the synthesis algorithm recently proposed, highlighting their advantages and drawbacks. Then, we show that, depending on the particular application scenario for which the sparse array must be designed, a better tailored algorithm exists. The presented analysis is aimed at providing a useful tool for antenna engineers involved in the overall design of sparse arrays for satellite communications.

Ensuring global coverage with isophoric direct radiating ring arrays

In this contribution we discuss the feasibility of a full-Earth coverage from GEO satellite by means of isophoric (that is, equi-amplitude) Direct Radiating Arrays (DRAs). By focusing on the ring-array architecture we show that a large beam scanning requirement imposes some severe geometrical constraints on the final array layout. Furthermore, we introduce a synthesis procedure capable to generate arrays satisfying the desired specifications with a reasonably low number of control points.