An array antenna includes a modular, multi-layer, multi-balun board structure for use in feeding a dual polarization radiating element. In some embodiments, contacts on a multi-balun board structure may be directly conductively coupled to corresponding feed points of a dual polarization radiating element during antenna assembly. The multi-balun board structure may be inserted into an opening within an aperture board of an array antenna before the contacts are secured to the feed points. Dual balun board structures may be provided for some or all of the radiating elements on the aperture board.