Decreasing antenna beamwidth with increasing scan angle

All antennas, including phased arrays, exhibit beam broadening in the near field and also beam broadening in the far field at scan angles off broadside. For scan angles in the near field, the effective aperture is reduced, thereby producing less beam broadening due to the near field. At any scan angle, there is a near-field distance at which the broadside far-field beamwidth plus broadening equals the scan angle far-field beamwidth plus broadening. For larger scan angles, the beamwidth is less than at broadside. Calculations of this phenomenon are made for uniform linear and for tapered circular apertures.