Full probe-correction for near-field antenna measurements

Nowadays antenna measurements are often carried out exploiting the benefits of near-field transformation techniques. The transformation algorithms usually applied require near-fields being measured in two polarisations in order to calculate an equivalent spherical multipole representation of the antenna under test (AUT). Although it is desirable to use custom probes for various applications, especially in research. Custom probes generally do not satisfy the first-order requirement. On the other hand it is well known that a treatment of custom probes as first-order probes will lead to significant errors when calculating the far field from these insufficiently corrected near-field measurements. In this paper it is shown that this error is even worse when dealing with near-field to near-field transformations as required for antenna diagnostics. However the impact on the quality of the transformed near-field data is significantly reduced when applying our proposed probe correction algorithm. The results of the near-field transformations therefore provide significantly improved far-fields as well as an adequate basis for calculating the electromagnetic fields in the proximity of the AUT for diagnostic purposes.