Abstract
Large computational electromagnetic problems for scattering from forest canopies in L-band (1–2 GHz) typically require modeling trees by a collection of lossy, dielectric cylinders and disks using Multiple Body of Revolution (MBOR) scattering techniques. MBOR techniques are desired for their computational efficiency compared to the 3-D Method of Moments (MoM). Within the vegetation environment associated with forest canopy, BORs are weakly coupled and, thus, approximations may be made to improve computational efficiency of MBOR scattering. This paper develops an efficient method to calculate the scattered fields from a lossy, finite length, dielectric cylinder, illuminated by a small current source. A small current source is representative of those on an adjacent BOR in MBOR scatter. Computational solutions to this problem exist, but those solutions are complicated and computationally expensive. Using the proposed method, a BOR is discretized into a series of discs such that far field conditions are a function of BOR radius rather than BOR length. These field conditions define the Localized Plane Wave Approximation (LPWA), which provides foundation for a more system specific MBOR scattering methodology, where BORs are harmonically independent of each other. For LPWA validation, the LPWA is compared to both analytical and computational solutions. The approximation shows good agreement within the constraints of the underlying assumptions. Finally, the method improves computational efficiency by more than an order of magnitude.