An antenna for transmission of a radio-frequency, RF, wave, the antenna comprising: a stack-up structure having: a first control layer; a second control layer being approximately parallel to the first control layer; a first parallel-plate waveguide and a second parallel-plate waveguide located between the first control layer and the second control layer, the first parallel-plate waveguide and the second parallel-plate waveguide being approximately parallel to each other and to the first control layer and the second control layer; and a plurality of through vias configured to operatively connect the first control layer and the second control layer to ground layers (103,204), the ground layers (103, 204) being connected to an electrical ground; a first central port located on the first control layer and a second central port located on the second control layer, the first central port being configured to radiate the RF wave into the first parallel-plate waveguide, and the second central port being configured to radiate the RF wave into the second parallel-plate waveguide; vertical-polarization peripheral ports integrated with the first control layer and configured to radiate the RF wave in vertical polarization from the first parallel-plate waveguide; and horizontal-polarization peripheral ports integrated with the second control layer and configured to radiate the RF wave in horizontal polarization from the second parallel-plate waveguide, each one of the vertical-polarization peripheral ports being collocated with one of the horizontal-polarization peripheral ports such that they cross each other. a stack-up structure having: a first control layer; a second control layer being approximately parallel to the first control layer; a first parallel-plate waveguide and a second parallel-plate waveguide located between the first control layer and the second control layer, the first parallel-plate waveguide and the second parallel-plate waveguide being approximately parallel to each other and to the first control layer and the second control layer; and a plurality of through vias configured to operatively connect the first control layer and the second control layer to ground layers (103,204), the ground layers (103, 204) a first control layer; a second control layer being approximately parallel to the first control layer; a first parallel-plate waveguide and a second parallel-plate waveguide located between the first control layer and the second control layer, the first parallel-plate waveguide and the second parallel-plate waveguide being approximately parallel to each other and to the first control layer and the second control layer; and a plurality of through vias configured to operatively connect the first control layer and the second control layer to ground layers (103,204), the ground layers (103, 204) being connected to an electrical ground; a first central port located on the first control layer and a second central port located on the second control layer, the first central port being configured to radiate the RF wave into the first parallel-plate waveguide, and the second central port being configured to radiate the RF wave into the second parallel-plate waveguide; vertical-polarization peripheral ports integrated with the first control layer and configured to radiate the RF wave in vertical polarization from the first parallel-plate waveguide; and horizontal-polarization peripheral ports integrated with the second control layer and configured to radiate the RF wave in horizontal polarization from the second parallel-plate waveguide, each one of the vertical-polarization peripheral ports being collocated with one of the horizontal-polarization peripheral ports such that they cross each other.