Deep Thinning of MoM Matrices with the Balanced Electromagnetic Absorber Method in 3 Dimensions

A balanced (Weston-type) absorber, characterized by both electric and magnetic loss mechanisms, can be placed within the null field inside the equivalent surface currents replacing a perfectly conducting or homogeneous scatterer. The absorber, referred to as the filler, substantially reduces interactions between pairs of opposing basis/testing functions. The resultant moment matrix, formulated with the filler Green's function, is thinned accordingly. Moreover, most annulled elements need not be computed at all, thereby reducing substantially the matrix fill time. The lossy nature of the Green's function also serves to eliminate spurious internal resonances and thus makes the electric or magnetic field integral equation matrix well conditioned without resorting to a combined field integral equation.