Probe Compensated NF-FF Transformation with Helicoidal Scanning

Abstract

A new cylindrical near-field- far-field transformation technique, which uses the helicoidal scanning for the near-field data acquisition, is proposed. From the theoretical viewpoint it is based on an innovative non-redundant sampling representation of the electromagnetic field over a circular helix. A fast, accurate and stable interpolation algorithm is developed to reconstruct the near-field at any point required by the classical near-field- far-field transformation technique with cylindrical scanning. Then the ideal probe assumption is removed and it is shown that the antenna far-field pattern can be efficiently calculated from the knowledge of a non-redundant number of output probe voltage samples over a circular helix. Many numerical tests assess the effectiveness of the far-field reconstruction process, in spite of the reduced number of employed near-field data, as compared with the classical cylindrical scanning.