Spherical near-field scanning: determining the incident field near a rotatable probe

A spherical near-field scanning algorithm is developed for determining incident fields inside a probe´s minimum sphere. This differs from the well-known spherical near-field scanning formulation which determines fields outside the source´s minimum sphere. The scanner size depends on the extent of the region of interest and not on the extent of the (possibly much larger) source. The data can be collected using a standard roll-over-azimuth positioner. The practical implementation of this technique is discussed.<>