Probe Correction Technique of Arbitrary Order for High Accuracy Spherical Near Field Antenna Measurements

Technical Publications
Tuesday, November 29, 2016

Probe  correction  in  standard  spherical  near field measurements are typically limited to probes with |μ|=1 spherical wave spectrum when performing spherical wave expansion. The design of such probes is often a trade-off between achievable performance,  modal  purity  and bandwidth. Compensation techniques for probes with higher or full order modal spectrum have  recently  been  proposed. The  advantages of  such techniques are more freedom in the selection of the probe for a given  measurement scenario  and  increased  bandwidth.  The technique reported in this paper is valid for probes with a known modal  spectrum  of  arbitrary order. Probe  compensation  is performed  directly  on each  spherical  wave  function  before expanding the  measured  field.  This  leads  to  a computationally very effective  algorithm.  In this paper, the  accuracy  of the new  algorithm  is  validated  experimentally  for  different  higher order  probes  in  the  measurement  of  a  standard  gain horn. For each  scenario, the accuracy and computational requirement of the new algorithm is compared to standard transformations.