Assessment of Irregular Sampling Near-Field Far-Field Transformation Employing Plane-Wave Field Representation

Near-field antenna measurements are accurate and common techniques for determining the radiation pattern of an antenna under test. The minimum near-field sampling rate is dictated by the electrical size of the antenna. Equidistant sampling is usually applied for planar, cylindrical, and spherical measurements. Certain applications either rely on or benefit from near-field sampling on irregular grids. To handle irregular measurement grids, near-field transformation algorithms such as equivalent-current methods or the multilevel fast multipole accelerated plane-wave based technique are required, which do not rely on regularly sampled data. In this contribution, the plane-wave-based near-field transformation is applied to spherical, cylindrical, and “combined” near-field measurements employing irregular sampling grids. The performance is assessed by various simulated near-field-measurement scenarios.