A near-resonance decoupling approach (NRDA) for scattering solution of near-resonant structures

The generalized network formulation is applied in combination with the method of moments to calculate the electromagnetic scattering from conducting objects containing near-resonant open-ended cavities. The presence of the cavity increases the iteration number in conjugate gradient iterations due to the near-resonant modes and the multiple wave bounces inside the cavity. The equivalence principle is used to separate the cavity region from the rest of the object, allowing an independent solution of the cavity problem by a direct inversion algorithm using a connection scheme. The solution of the cavity is then represented by a generalized admittance matrix. Numerical results for two-dimensional (2-D) composite targets show that the iteration number can be reduced significantly for objects containing long cavities. This algorithm can also be applied to three-dimensional problems.