Theoretical and experimental study of spherical arrays

The spectral-domain approach to the analysis of the spherical antenna arrays is studied in the paper. The main advantage of transforming the original problem in the spectral domain is that the original three-dimensional problem is reduced to a spectrum of one-dimensional problems. Therefore, the Green´s functions needed for applying the moment method, as well as the elements of the moment method matrix, can be determined in the spectral domain. The main disadvantage lies in numerical problems appearing when the structures with large radii are analyzed. In order to avoid numerical problems a modified vector-Legendre transformation and normalized Legendre polynomials are defined and applied to the solution procedure. The abilities of the method are demonstrated on the analysis of the microstrip patch antennas and waveguide antennas mounted on the spherical supporting structure.