The disclosed structures and methods are directed to transmission and reception of a radio-frequency (RF) wave. An antenna comprises a stack-up structure having a first control layer, a second control layer, a first and a second parallel-plate waveguides, and a plurality of through vias. The antenna further comprises a first central port and a second central port being configured to radiate RF wave into the two parallel-plate waveguides independently; vertical-polarization peripheral radiating elements integrated with the first control layer and configured to radiate RF wave in vertical polarization; and horizontal-polarization peripheral radiating elements integrated with the second control layer and configured to radiate RF wave in horizontal polarization. Each vertical-polarization peripheral radiating element is collocated with one of the horizontal-polarization peripheral radiating element such that they cross each other. A central port for transmission of RF wave into the stack-up structure of the antenna is also provided.