The disclosed structures and methods are directed to antenna systems configured to transmit and receive a wireless signal in and from different directions. An antenna structure comprises a pair of horizontal-polarization (HP) antenna units forming a first parallel-plate waveguide. One of the HP antenna units and a base unit form a second parallel-plate waveguide. The antenna further comprises a pair of vertical-polarization (VP) antenna units each located in one of the first and second parallel-plate waveguides. Each HP antenna unit comprises inverted F antennas (IFAs) configured to radiate a radio-frequency (RF) waves that are horizontally polarized. Each VP antenna unit comprises VP excitation elements configured to radiate the RF waves that are vertically polarized. A method for manufacturing of the antenna structure is also disclosed.