A wireless device comprising: - an antenna array, wherein the antenna array comprises: ∘ a first set of antenna elements and ∘ a second set of antenna elements, the second set of antenna elements different from the first set of antenna elements; and - a feed network for the antenna array, wherein the feed network comprises: ∘ a first transmission line structure configured for propagating signals according to a first electromagnetic propagation mode corresponding to a Transverse Electromagnetic, TEM, or a quasi-TEM mode, the first transmission line structure operatively coupled to the first set of antenna elements of the antenna array; and ∘ a second transmission line structure for propagating signals according to a second electromagnetic propagation mode, the second electromagnetic propagation mode corresponding to one of a Transverse Electric, TE, and a Transverse Magnetic, TM, mode, the second transmission line structure operatively coupled to the second set of antenna elements of the antenna array; wherein the first transmission line structure is a stripline and the second transmission line structure is a waveguide and a conductor of the stripline is routed within an interior of the waveguide. - an antenna array, wherein the antenna array comprises: ∘ a first set of antenna elements and ∘ a second set of antenna elements, the second set of antenna elements different from the first set of antenna elements; and ∘ a first set of antenna elements and ∘ a second set of antenna elements, the second set of antenna elements different from the first set of antenna elements; and - a feed network for the antenna array, wherein the feed network comprises: ∘ a first transmission line structure configured for propagating signals according to a first electromagnetic propagation mode corresponding to a Transverse Electromagnetic, TEM, or a quasi-TEM mode, the first transmission line structure operatively coupled to the first set of antenna elements of the antenna array; and ∘ a second transmission line structure for propagating signals according to a second electromagnetic propagation mode, the second electromagnetic propagation mode corresponding to one of a Transverse Electric, TE, and a Transverse Magnetic, TM, mode, the second transmission line structure operatively coupled to the second set of antenna elements of the antenna array; wherein the first transmission line structure is a stripline and the second transmission line structure is a waveguide and a conductor of the stripline is routed within an interior of the waveguide. ∘ a first transmission line structure configured for propagating signals according to a first electromagnetic propagation mode corresponding to a Transverse Electromagnetic, TEM, or a quasi-TEM mode, the first transmission line structure operatively coupled to the first set of antenna elements of the antenna array; and ∘ a second transmission line structure for propagating signals according to a second electromagnetic propagation mode, the second electromagnetic propagation mode corresponding to one of a Transverse Electric, TE, and a Transverse Magnetic, TM, mode, the second transmission line structure operatively coupled to the second set of antenna elements of the antenna array; <EOS>