Imaging of Element Excitations with Spherical Scanning
Authors: Doren W. Hess, Scott T. McBride
Publication: AMTA 2011
Copyright Owner: NSI-MI Technologies
We review two conventional algorithms for aperture back-projection from spherical near-field data, with the goal of quantifying array-element excitations. The first algorithm produces that portion of the near field that radiates to the far field. The second algorithm divides out the element pattern prior to the transformation, and produces an estimate of the element excitations. We introduce a variation of this element-excitation algorithm that, for some arrays, can improve the fidelity of this conventional estimate. We apply the three algorithms to measured data, where the algorithms’ assumptions are tested, and to synthesized data, where the expected results are known exactly. For the array geometries measured and simulated, this new algorithm shows dramatic improvement.
Two of the three algorithms require an estimate of the element pattern, which they assume to be common to all the elements. We describe our measurement of our array’s element pattern, as well as the use of the IsoFilterTM to center the element pattern and limit the edge effects.