A Broadband Multipole Method for Accelerated Mutual Coupling Analysis of Large Irregular Arrays Including Rotated Antennas

We present a numerical method for the analysis of mutual coupling (MC) effects in large, dense, and irregular arrays with identical antennas. Building on the method-of-moments (MoM), our technique uses a macro-basis function (MBF) approach for rapid direct inversion of the MoM impedance matrix. To expedite the reduced matrix filling, we propose an extension of the steepest-descent multipole (SDM) expansion which remains numerically stable and efficient across a wide bandwidth. This broadband multipole-based approach is well-suited to quasi-planar problems and requires only the precomputation of each MBF’s complex patterns, resulting in low antenna-dependent preprocessing costs. The method also supports arrays with arbitrarily rotated antennas at low additional cost. A simulation of all embedded element patterns (EEPs) of irregular arrays of 256 complex log-periodic antennas completes in just 10 min per frequency point on a current laptop, with an additional minute per new layout.