An equivalent magnetic current (EMC) approach has been proposed as an alternative method to the classical modal formulation for computing the far-field pattern of a radiating antenna from planar near-field measurements. The attractiveness of this EMC approach includes the possibility of producing the correct far-field pattern in all regions in front of a planar antenna under test (AUT), a drawback of the classical modal formulation due to its dependence on the Fourier transform and assumptions which must be made about the field outside of the measurement zone, and its adaptability to both irregularly sampled and non-canonical near-field measurement surfaces. A drawback of the EMC approach, however, is its significantly larger computational requirements. A comparison of the EMC and classical modal approaches for near-field to far-field transformation is examined in terms of the resultant far-field patterns. Measurement results for a waveguide-fed slot array using the UCLA bi-polar planar near-field measurement scanner are presented. An implementation of the EMC approach for the bi-polar geometry is described and results obtained using different subsets of the measured bi-polar near-field data are presented and compared to that obtained using the classical modal approach.

Peer Reviewed