Source reconstruction as a diagnostics tool in advanced antenna measurements

Recently, a growing research effort has been aimed at the problem of reconstructing the extreme near field radiated by the antenna from measured field data. Inverse source or the equivalent current/source method (EQC) based on discretization of integral equations has attracted considerable attention due to a host of promising applications in antenna design and diagnostics [1]-[8]. The integral equation approach constitutes a complement to more established tools such as plane-wave or spherical-wave expansion. At the expense of heavier computational burden this method offers a greater generality and flexibility since it allows reconstructing sources on any arbitrary 3-D surfaces enclosing the antenna under test (AUT). In [8] a unified EQC formulation was presented, in which the Equivalence Theorem is used to determine the set of equivalent electric and magnetic sources fully representing the fields on the reconstruction surface. This allows the extreme near field to be reconstructed from measured field data. The spatial filtering properties of the new EQC formulation was reported in [9]-[10] in which the method was shown to be efficient at eliminating radiation contributions from unwanted sources such as scattering from cables and support structures. In this work we examine the application of the EQC method as a diagnostics tool in practical measurement situations on different antennas recently reported in the literature [11]-[12]. An investigation of the level of details obtainable in practical measurement situations is also reported.