Auxiliary Dipoles to Compensate for the Finite Size of the Planar Scanning Area in Near-to-Far-Field Transformations

A novel algorithm to obtain an accurate representation of the far-field emissions starting from a finite planar scan of the magnetic near-field is proposed. The algorithm introduces so-called auxiliary sources that compensate for the finite size of the scan area. While previous works typically introduce equivalent sources to represent the fields inside the scanning area, the auxiliary sources introduced in this paper approximate the fields outside of the scanning area. The auxiliary sources are located within the printed circuit board under the scanning area at the locations where the scanned field strengths are above a prechosen threshold. Their complex values are chosen such that they accurately represent the fields at the edge of the scanning area. Several numerical examples show that the application of these auxiliary sources considerably improves the accuracy of the obtained far-field.