Control of microstrip antenna radiation characteristics by ground plane size and shape

The effects of various physical and electrical parameters of circular microstrip patch antennas on their radiation characteristics are investigated. These parameters include the ground plane size, substrate permittivity, ground plane and substrate thicknesses and the ground plane shape. The investigation is carried out for the first four modes. A numerical method based on the moment methods is utilised which computes surface currents on the conductors and field distributions on the dielectric substrate. To avoid excessive computation, circular patch and ground planes are selected to allow the use of moment method for bodies of revolution. Initially, a circular patch with a finite ground plane is studied. The ground plane is then deformed, above and below the substrate, to increase the gain or shape the radiation patterns. It is shown that the ground plane effects are significant and a wide range of radiation pattern shapes can be generated