Direct Determination of the T-Matrix From a MoM Impedance Matrix Computed Using the Rao-Wilton-Glisson Basis Function

Theory of Near-Field Scanning with a Probe Array

“…For a simple probe such as the dipole probe, we may determineŜ using a computational technique. In our recent research, we have shown that the "effective T-matrix," τ (Z L ), which relates the incoming field to the total outgoing field, can accurately be determined directly from the method-of-moment impedance matrix based on the electric field integral equation (EFIE) and the Rao-Wilton-Glisson basis function [12]. We have also applied a similar technique to the EFIE with the thin-wire reduced kernel and the one-dimensional roof-top basis function to extract τ (Z L ) for an arbitrarily loaded linear dipole probe [20].…”

“…, of the ith probe element with i = 1, ..., N , in the combined presence of the other N − 1 probe elements and of the DUT. Due to MS and MC, they will deviate from their isolated, free-space counterparts, (3), that can be determined using the extraction techniques discussed above [12] [14]. In the presence of the probe array, the T matrix of the DUT,T tg , will also deviate from the corresponding isolated, free-space counterpart, T tg .…”

“…Shown in Figure 6 is the comparison of the FF pattern computed using the formalism presented above with the NEC-4 [21] result for the scattering from three loaded dipoles shown in Figure 7. The dipole antenna scattering matrix was computed using the extraction technique discussed in [14]. The agreement between the two curves is excellent.…”

“…This approach is ideal for investigating MS and MC effects involving electrically small-to moderate-size probes. Its chief advantage is that the number of unknowns, which ultimately determines the overall computational cost, is often lower than those associated with more popular numerical approaches [12], such as the method of moments. Furthermore, with this approach it is less cumbersome to separate the MS and MC contributions from the total fields, making it correspondingly less troublesome to assess the extent of multiple-interaction effects.…”

Fast superposition T-matrix solution for clusters with arbitrarily-shaped constituent particles

“…For the T-matrix determination, we expand the electric Green's dyadic in the VSWFs and construct so-called transformation matrices linking the VSWF coefficients to the MoM basis function coefficients. A similar approach has been used previously to examine the scattering by perfect electric conductors using the surface integral equation [15]. Furthermore, we compute the T-matrix iteratively with the matrix-vector multiplication accelerated by the precorrected-FFT method [16].…”