A grid array antenna with parasitic monopoles

A system composed of a grid array antenna (GAA) and parasitic monopoles is analyzed. The analysis is performed using an integral equation with the method of moments to reveal the radiation pattern, axial ratio, half-power beam-width and gain. It is found that the parasitic monopoles contribute to transforming a linearly polarized beam from the GAA into a circularly polarized beam. It is also noted that this circularly polarized beam is almost symmetric with respect to the antenna axis normal to the GAA.