Reducing the complexity of the beam calibration models of phased-array radio telescopes

The present day radio telescopes with single-beam feeds can achieve the dynamic range up to 10⁶:1 in the beam on-axis direction. However, the off-axis dynamic range is severely limited by uncertainties and temporal instability in the beam patterns. A number of calibration techniques for dealing with these effects have been proposed and used in practice. For nove lphased-array based telescopes, the beam calibration is a new challenging field and no clear consensus on what constitutes a `good´ beam pattern exists yet. The common denominator of the currently developed techniques, however, is smoothness in the beam patterns. The presented beamforming strategy therefore aims to realize circularly symmetric patterns of multiple beams that can be described by smooth analytic (e.g. Gaussian or elliptical) models.