A New Model for Scattering From Tree Canopies Based on Physical Optics and Multiple Scattering Theory

A New Propagation Channel Synthesizer for UAVs in the Presence of Tree Canopies

“…Recently, the authors have developed in [7] a new model addressing scattering from tree canopies which significantly lowers the corresponding requirements by replacing MST coherent field calculations by utilizing the physical optics (PO) approach based on [8]. In this way, near-field effects close to the canopy are modeled properly and smooth transitions between LoS and shadowed areas behind the canopy are achieved [7].…”

“…In this paper, we follow the model developed in [7] and, by adding the incoherent scattered field obtained by MST, we build a new propagation channel synthesizer for UAVs operating in close vicinities of tree canopies, which enables the generation of site-specific time series of received signal levels. This means that the output of this synthesizer can directly be utilized to obtain first-and second-order characteristics of the received signal for a particular scenario, i.e., respecting the positions of UAV, the terminal and trees, including the physical parameters of the canopies, such as dimensions and types of branches and leaves.…”

“…In Section 2, we present the theoretical background for PO and MST and we introduce the mixed PO/MST model developed by the authors in [7]. In Section 3, we build the new channel synthesizer based on the models presented in Section 2.…”

“…When applying common PO as given in [8] or [9], the equivalent electric J eq and magnetic M eq currents on the part of the object's outer surface illuminated by the incident fields E inc and H inc need to be calculated using the free space wave number k 0 , the incident plane wave directionk inc in the form of a unitary vector form k, and the outward pointing unit normal vectorn at each surface sample r (see [7]). Now, to obtain the fields scattered from the surface samples of areas dS , we utilize the near field propagators from [8] and, at point of interest r, we obtain the scattered magnetic field H scat,J based on J eq , the scattered electric field E scat,M based onM eq , the electric field E scat,J associated with H scat,J , and the magnetic field H scat,M associated with E scat,M .…”

“…Now, to obtain the fields scattered from the surface samples of areas dS , we utilize the near field propagators from [8] and, at point of interest r, we obtain the scattered magnetic field H scat,J based on J eq , the scattered electric field E scat,M based onM eq , the electric field E scat,J associated with H scat,J , and the magnetic field H scat,M associated with E scat,M . For more details see [7]. These scattered fields represent the blockage of the original fields E dir and H dir , which would be present at r under LoS propagation conditions without any obstruction.…”