An antenna structure includes a radiative antenna element disposed in a first conductive layer, a reflector ground plane disposed in a second conductive layer under the first conductive layer, a feeding network comprising a transmission line disposed in a third conductive layer under the second conductive layer, and at least one coupling element disposed in proximity to a feeding terminal that electrically couples one end of the transmission line to the radiative antenna element. The coupling element is capacitively coupled with the feeding terminal.