Range-dependent beamforming using element level waveform diversity

This paper presents a novel concept for focusing an antenna beam pattern as a function of range. In conventional phased arrays, beam steering is achieved by applying a linear phase progression across the aperture. Without this phase progression, the antenna beam points to broadside. However, a linear phase progression causes the electric field from each element to constructively sum in the far-field in a direction off broadside, resulting in an electronic scan. For a given linear phase progression, this scan remains fixed for all ranges in the far field. This paper shows that by applying an additional linear frequency shift across the elements, a new term is generated which results in a scan angle that varies with range in the far-field.