Broadside parallel-plate slot antenna without dielectric

A linearly polarized flat antenna with broadside beam radiation is presented. A rectangular slot array in the upper side of a parallel plate waveguide forms the main antenna structure. In previous works, the authors have presented one and dual tilted-beam antennas (see Castaner, M.S. et al., IEEE AP-S, vol.3, p.1608-11, 2000; Proc. AP-2000 Millennium, 2000) for the reception of Hispasat or Astra satellite emissions in the 12 GHz band. The problem of the broadside beam antenna is to avoid the grating lobes. The main goal of the work presented here is getting a low cost broadside antenna that does not need a dielectric material inside the parallel plate to solve the grating lobes problem.