Wideband Grating-Lobe Suppression by Rotation of the Phased Array Stations in the SKA Low-Frequency Sparse Aperture Array

A simple cost-effective technique of wideband grating-lobe (GL) suppression by rotation of the phased array antennas is developed for application in a system of low-frequency sparse aperture array (LF-SAA) antennas of the square kilometer array (SKA) radio-telescope. The technique implies using of equal sparse planar circular antennas with the well-tried square lattice (SqL) distribution of the station antenna array sensors, which is known as the best in terms of production costs and maintenance charges. The peak levels of residual GLs in the fringe pattern of most pairs of the rotated antenna array stations do not exceed value of -17 dB over frequencies ranged from 70 to 450 MHz in the case of uniform antenna array element weighting, whereas the maximum levels of residual GLs are reduced to -25 dB when the Hamming weight tapering is applied.