Moment method analysis of rectangular microstrip antennas on spherical structures

The interest for spherical arrays is based on their possibility to direct single or multiple beams through a complete hemisphere. Arrays of rectangular microstrip patches embedded in a multilayer spherical structure are analyzed using the spectral-domain approach and the moment method. In order to avoid numerical problems a modified vector-Legendre transformation and normalized Legendre polynomials are defined and applied to the solution procedure. The influence of structure radius on the input impedance and the resonant frequency of the spherical rectangular microstrip patch antenna are studied. A laboratory model is built to test different configurations of patches and to validate the calculated results.