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Foliage Propagation Model Development to Support New Communications Concepts


OBJECTIVE: Develop detailed foliage propagation models applicable to multiple environments that will support creation and analysis of new communications concepts that greatly exceed the operational performance of current systems in these environments. DESCRIPTION: The need for propagation models that extend beyond free space and urban environments into foliage-rich environments is well-known. The rising need for communications in forests, jungles and triple canopy environments shows the importance of characterizing these RF environments. This will allow for real-time situational awareness, sensor and command and control data throughout the entire battle space. Traditional communications through dense foliage and vegetations is challenged by severe multipath and attenuation thereby limiting the warfighter"s access to critical data. There is little to no data on RF propagation across the entire frequency spectrum through the various foliage elements and current models, such as FOREST, typically view foliage environments as a uniform dielecteric slab and are limited by the assumptions that they treat forests as reasonably uniform, the floor as absorptive, and only address frequencies up to approximately 1 GHz. A model is needed that can address the entire range of spectum, including current military radio systems, new 4G wireless technologies, millimeter wave communications (30-300 GHz), and can be equally applied to forest and jungles that are assumed to be non-uniform. A more thorough understanding of how RF signals act in these areas will allow for a communications concept to be developed that will overcome these challenges and limitations. The model will be combinable with other RF models to create a single, comprehensive RF propagation model. PHASE I: Perform a study on RF propagation through various types of foliage and provide the framework for a comprehensive foliage propagation model. The study should analyze the effects of multipath, attenuation and dispersion and be capable of statistical characterizations of system performance. It should analyze current limited models to decide if these models can be leveraged to support the new model and investigate other technologies that may provide indirect information that could be utilized or adapted such as information from LandSat imagery or foliage penetrating radars. This analysis will include RF properties from multiple types of foliage, trees and vegetation to provide a basis for the study. Phase I should result in the framework for a comprehensive foliage propagation model in Phase II. PHASE II: Develop a comprehensive foliage model to accurately predict RF propagation through multiple types and densities of vegetation. The model will be validated and tested using government provided emperical data as well as real-world measurements obtained from field testing in various enviornments across the full spectrum of frequencies. The model will then be used to support a separate research and development program of new communications technologies and systems with performance capabilities beyond current systems operating within these environments, e.g. increased communications range, accuracy, capacity, bandwidth and reduced equipment size, weight and power. Phase II will result in a comprehensive, working foliage penetration model that can be applied to current and future communications systems in these type environments. The technology readiness level at the end of this phase will be a minimum Level 6. PHASE III: The system should be applicable to commercial and homeland security operations in dense, foliage-rich environments. A military prototype communications system, based on the results found from the Phase II foliage propagation model, should be designed, field tested and verified. Potential interested military organizations include the Defense Spectrum Organization (DSO) and CERDEC"s Space&Terrestrial Communications Directorate, specifically the Antennas&Spectrum Analysis Division.
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