An antenna array includes multiple array modules. Each array module includes at least on antenna element including a horn antenna coupled to a polarizer, and a two-piece waveguide filter. The two-piece waveguide filter includes a folded-back waveguide coupled to the horn antenna at one end and to a circuit layer at the other end. The horn antenna includes a multi-mode horn antenna. The two-piece waveguide filter includes a first piece and a second piece that are separately molded. A footprint of the two-piece waveguide filter is within a footprint of an aperture of the horn antenna.