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 , the ground layers 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 , the ground layers 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 , the ground layers 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. <EOS>