Antenna unit cells suitable for use in antenna arrays are disclosed, as are antenna arrays and mounting platform such as an aircraft comprising antenna unit cells. In one embodiment, an antenna unit cell comprises a signal feed line, a ground plane, a first antenna element comprising a first antenna arm coupled to the signal feed line and a second antenna arm coupled to the ground plane, and a first narrow-band conductor coupled to the first antenna arm and to the ground plane. Other embodiments may be described.