Sub spectra representation of antennas for plane wave based near-field far-field transformation at short measurement distances

Near-field antenna measurement and transformation techniques allow to accurately determine the radiation pattern of an antenna under test. The plane wave based near-field far-field transformation algorithm is a flexible technique which allows to measure the radiated antenna field on an arbitrary measurement grid, to utilize arbitrary probe antennas, and which has a low numerical complexity. However, as all techniques employing Hankel functions, the algorithm is limited in the case of electrically very short measurement distances. In this paper a sub spectra representation is presented which subdivides the antenna into smaller source regions thus circumventing the aforementioned problems.