Depolarisation studies of single trees at 20 GHz

This paper addresses the characterization of the polarization states of the re-radiated signal from a natural tree performed in the vicinity around deep signal fades, at 20 GHz. The polarization pattern method has been used to investigate the effects of depolarization and to further characterize the changes in the polarization state of the re-radiated signal occurring as a result of the currents induced in the trunk, branches and leaves, which are significantly influenced by the complex permittivities of the various materials making up the tree. Results presented in the paper will explain the signal behavior observed in the various regions around the tree. The results also show that depolarization, in addition to absorption and scatter, is an important factor formulating accurate models for propagation in vegetation.info:eu-repo/semantics/publishedVersio

Simplified RET model derived from path loss and directional spectrum measurements in vegetation media at 11.2 and 20 GHz

This study presents a simplified radiative energy transfer (RET) model derived from path loss and directional spectrum measurements in vegetation media at 11 and 20 GHz. Thus, a simplified extraction procedure for the inputs parameters based on the method foreseen by the international telecommunications union - recommendation (ITU-R) P.833-8, however for isolated vegetation volumes, is proposed. Results for specific measurements aimed at the extraction of the RET model parameters are subsequently presented and discussed. The extraction method relies on a limited set of propagation measurements to find and optimise the RET input parameters. Specific measurements of the received signal directional profile are used to show the applicability of the method. This parameter evaluation method is tested and assessed based on the received signal directional profile measurements performed in Populous trees at 11.2 and 20 GHz.info:eu-repo/semantics/publishedVersio