Near field calculations with far field formulas

We discuss a method for using far field formulas to calculate near field effects by decomposition. The method uses complex scattered amplitudes rather than radar cross sections as inputs, and therefore has certain advantages over the scattering centers approach. We discuss a physical optics (PO) technique for calculating the scatter in the near field of a large target or reflector. It is assumed that the target has been decomposed into a number of smaller pieces, each of which is in the far field of the transmitter and receiver.