A New Design Tool for Shaping the Radiation Pattern of Patch Antennas

Recently, we have presented several configurations of microstrip antenna, which exhibit peculiar radiation characteristics due to the topological properties of the vortex modes radiated by the antenna itself. In particular, the performances of these structures are all related to the proper superposition of two different circular polarized modes of patch antennas, radiated by two concentric radiating elements. In this contribution, we show that the proposed configurations are particular cases of a more general design tool, which can be exploited for shaping the radiation pattern of patch antennas in many other different forms. In particular, being the pattern shaping capabilities related to the positions of phase singularity points in the overall radiated beam, we determine the equations that relate the singularity locations to the structural and feeding properties of the radiating structure. Moreover, as a practical example, we show the conditions that allow designing a single radiating structure with a multi-beam radiation pattern.