An `add-on' method for the analysis of scattering from large planarstructures

A so-called add-on procedure is proposed to deal with the data analysis problem resulting from the collection of scattering data from large planar structures. The computations (involving of the order of a few thousand unknowns) is undertaken in a gradual manner by building up the body from small patches which are added sequentially. The procedure is based on an initial expansion of the unknown current distribution into subsectional (pulse-type) basic functions. Each segment of the scatterer carries an unknown amplitude which is the response to an incident wave. However, rather than forming a matrix equation for these responses, they are computed in a gradual manner where the scatterer is built up from these segments as they are added one at a time. At the end of each addition of a segment, the result for scattering from a partial body is obtained. At each stage, the problem solved reflects the size of the small addition only, and the solution to an actual partial body is obtained. An important feature of this method is its ability to utilize a priori known information on a portion of the scatterer as an initial stage for the economic analysis of the entire structure. The process takes into account the interactions between all segments of the body. The process proves to be very efficient both in terms of computation time and storage requirements, as seen in the computed examples on of the order of 1000 to 6000 unknowns