Constructing matrix Green´s functions for radiation and scattering problems

A method for constructing a Green´s function for an arbitrary scatterer or antenna consisting of multiple parts is presented. By exploiting the partitioning of the impedance matrix that naturally develops in a method-of-moments (MM) formulation when a number of objects are present, a matrix of numerical values representing the fields of one object in the presence of all others is computed. This matrix may be stored and used repeatedly when one of the scatterers or antennas is varied in location or shape. The matrix Green´s function approach is also extended to represent incrementally larger objects. Savings in computation time over using the free-space Green´s function and re-solving the large MM matrix repeatedly are considerable. The proposed technique has been implemented on the JPL/CIT Mark III Hypercube Computer and applied to radiation and scattering from a large array.<>