A fast MoM solver (GIFFT) for large arrays of microstrip and cavity-backed antennas

A straightforward numerical analysis of large arrays of arbitrary contour (and possibly missing elements) requires large memory storage and long computation times. Several techniques are currently under development to reduce this cost. One such technique is the GIFFT (Green´s function interpolation and FFT) method that belongs to the class of fast solvers for large structures. This method uses a modification of the standard AIM approach (Bleszynski, E. et al., Radio Science, vol.31, p.1225-51, 1996) and takes into account the reusability properties of matrices that arise from identical array elements. The method has been proven to give a greatly reduced solving time. The GIFFT approach also reduces fill time and memory requirements, since only the near element interactions need to be calculated exactly. The paper extends GIFFT to layered material Green´s functions and multiregion interactions via slots in ground planes. In addition, a preconditioner is implemented to give a great reduction in the number of iterations required for a solution. The paper presents new results for array antennas made of slot-excited patches and cavity-backed patch antennas.