A slotted waveguide antenna stiffened structure for an aircraft having an aircraft skin. The slotted waveguide antenna stiffening structure including a structural stiffening element reinforcing the aircraft skin; the structural element connected to a radio frequency feed source, the source providing energy with electromagnetic bandwidth to a slotted waveguide antenna having a plurality of slots. The antenna conformal to the aircraft skin and the structural stiffening element, the structural stiffening elements functioning as waveguides for the electromagnetic bandwidth. The slots may include a slot sealant enclosing the plurality of slots.