Near-field scattering methods applied to radio-propagation modeling in urban outdoor environments

In this paper a time-efficient method for the calculation of the scattered field from rectangular plates (walls) in the near and Fresnel zone is presented. The method, which we call 'Near to Far Field Transformation Method', is based on the analytical method of Physical Optics (PO) and uses the technique of segmentation of the scattering surface into an appropriate number of small rectangles (cells). By such a division of the large scatterer, an observation point which is originally located in the near or Fresnel zone of the scatterer, is now transferred/relocated to the far zone of the smaller cells. As a result, the PO far-field approximations, which use the easy-to-compute sine (sin(x)/x) function, can be invoked in order to calculate the electromagnetic field at the receiver due to the induced PO currents at each cell. The total scattered field at the receiver's position is calculated by complex vector addition of all signal components received.