Abstract: A modular wideband antenna includes a ground plane, first and second antenna elements disposed on a first surface of a substrate, a first portion of a two-layer feed balun disposed on the first surface of the substrate, and electrically coupled to the first and second antenna elements, and to the ground plane, a second portion of the two-layer feed balun disposed on a second surface of the substrate, the second portion of the two-layer feed balun being electrically coupled to a signal feed, and being capacitively coupled to the first portion of the two-layer feed balun, first and second coupling capacitances disposed on the second surface of the substrate, the first coupling capacitance being capacitively coupled to the first antenna element, and the second coupling capacitance being capacitively coupled to the second antenna element, and first and second grounding posts being electrically coupled to the first and second coupling capacitances.