Low Sidelobe Pattern Synthesis of Array Antennas With a Triangular or Skew Lattice Using the IFT Method

This paper deals with the update of the iterative Fourier transform (IFT) method that makes this method suitable for the low sidelobe pattern synthesis of array antennas having a triangular or skew lattice. This update comprises the replacement of the two main components of this synthesis method which are the FFTs, direct and inverse, by new ones which can deal with the processing of signals arranged along a triangular or skew lattice. Present 2D FFTs can only be applied to array antennas with the elements positioned in a rectangular or square grid. The paper describes how the present 2D FFTs, direct and inverse, only applicable for rectangular lattices, can be modified in a simple way to make them suitable for the processing signals arranged along a triangular or skew grid. These two modified FFTs are subsequently implemented in the IFT method. The IFT method, updated in this way, is then very suited for the low sidelobe pattern synthesis of array antennas with a triangular lattice or skew lattice. Four low sidelobe pattern synthesis examples obtained with the updated IFT will be given. Two of them refer to an array antenna with triangular lattice. The other two to an array with a skew lattice.