Exemplary embodiments are disclosed of antennas, antenna systems, and methods of making antennas. In an exemplary embodiment, an antenna generally includes a ground plane and first and second antennas each including a first feed. The antenna system further comprises a neutral line having first and second end portions coupled to the first feed of the respective first and second antennas, and/or one or more decoupling stubs integrally formed from and extending outwardly relative to the ground plane. In another exemplary embodiment, a method of improving isolation between first and second antennas of an antenna system generally includes coupling first and second end portions of a neutral line to a first feed of the respective first and second antennas, and/or integrally forming one or more decoupling stubs from a ground plane.