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.