A method for radiating a co-located antenna including radiating the co-located antenna using a dual mode, where the co-located antenna has an inter-element spacing of about 1λ and the dual mode includes a TM11 mode and a TM21 mode. The TM11 mode is radiated to generate a TM11 far field pattern, where the TM11 mode has a broadside pattern characterized with a beam peak at broadside and the TM11 mode produces grating lobes in addition to the beam peak at broadside. The TM21 mode is radiated to generate a TM21 far field pattern orthogonal to the TM11 far field pattern, thereby causing the TM21 mode to produce a null at broadside to suppress the grating lobes produced by the TM11 mode.