A far-field transformation from phaseless near-field data on helicoidal geometry

An efficient far-field transformation is developed from near-field phaseless data on a cylindrical helix. Amplitude information collected by an integrated probe are processed to obtain the near-field phase, with a retrieval procedure performed along the single helicoidal curve. A fast Fourier transform based algorithm is directly applied to complex helicoidal near-field data to obtain antenna far-field pattern, so avoiding any intermediate interpolation on cylindrical surfaces. The proposed approach is numerically validated on a uniformly spaced array of dipoles.