Ricerc@Sapienza

In this paper, aliasing effects are investigated for random fields defined on the d-dimensional sphere Sd and reconstructed from discrete samples. First, we introduce the concept of an aliasing function on Sd. The aliasing function allows one to identify explicitly the aliases of a given harmonic coefficient in the Fourier decomposition. Then, we exploit this tool to establish the aliases of the harmonic coefficients approximated by means of the quadrature procedure named spherical uniform sampling.

A radially periodic two-dimensional leaky-wave antenna is studied for the generation of zeroth-order Bessel beams within a limited spatial region and over a wide frequency range. The antenna design is wideband and based on an annular metal strip grating placed on top of a grounded dielectric slab, supporting a cylindrical leaky wave with a fast backward spatial harmonic.