Fast Wideband Monostatic Scattering Analysis Method Combining Macro-Block Characteristic Basis Function Method With Improved FIR for Freestanding Large-Scale Finite Periodic Arrays

An efficient numerical method for the wideband scattering analysis of the freestanding large-scale finite periodic array is presented using the macro block-characteristic basis function method (MB-CBFM) and the improved frequency-independent reaction (FIR). In the MB-CBFM, the blocks (unit cells) are divided into some types of macro blocks. By analyzing the subarray with the macro blocks, the CBFs for the macro blocks will be obtained. The blocks in the same macro block share the same CBFs. Substituting the CBFs into the moment matrix equation, a reduced matrix equation whose size does not depend on the number of the blocks can be obtained and handled utilizing direct methods. When the MB-CBFM is applied for wideband analysis, the matrix needs to be recomputed. The reduced matrix can be efficiently generated by using the improved FIR, in which the matrix elements are expressed as the product of the geometrical elements and the phase factor. The geometrical elements are computed one time and reused. Only the phase factor needs to be recomputed. Several numerical examples are carried out. Simulation results show that the results of the proposed algorithm agree well with those of other numerical methods. The total CPU time is significantly reduced.