Front-to-back ratio improvement of a microstrip patch antenna by ground plane edge shaping

In a microstrip patch antenna design on the finite size of ground plane, it shows significant performance degradation by surface waves. It is well known that the smaller ground plane size, the gain is decreased and the back lobe is increased. As the size of the ground plane is reduced, currents distribution of the ground plane edge is increased. These currents results in diffraction of both leaky and surface waves and the front-to-back ratio of a patch antenna is decreased due to the increased backward wave level. In this paper, ground plane edge shaping method is used to reduce these edge currents effect. By cutting out the edges of the ground plane of the patch antenna and forming the meandering edges, the front-to-back ratio of a patch antenna significantly improved.