Physics-Based Near-Earth Radiowave Propagation Modeling and Simulation.

Radiowave Propagation;Electromagnetics;Near-earth Radiowave Propagation;Physics-based Modeling;Unattended Ground Sensors;Antennas;Electrical Engineering;Engineering;Electrical Engineering

Liao, Da HanStark, Wayne E. ;

University of Michigan

关键词: Radiowave Propagation;    Electromagnetics;    Near-earth Radiowave Propagation;    Physics-based Modeling;    Unattended Ground Sensors;    Antennas;    Electrical Engineering;    Engineering;    Electrical Engineering;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/62371/liaod_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Both the efficacy and accuracy of existing algorithms for predicting radiowave coverage are often compromised for the region proximate to the ground surface where grazing incidence (and wave cancellation) occurs, surface wave propagation predominates, and intricate higher order reflection and diffraction phenomena become important. A challenge of ongoing interest is to develop high-fidelity electromagnetic models that can reliably evaluate wave interaction with a realistic terrain over long distances with the inclusion of ground proximity effects—in order to support channel performance assessment and grid planning of near-ground (or even sub-surface) communication systems and sensing-oriented networks. In the featured study, physics-based propagation models enabling accurate calculation of propagation path-loss among the nodes of the VHF (30 MHz – 300 MHz) near-earth wireless system deployed in natural scenes are assembled through a compilation of analytical, numerical, experimental, and hybrid approaches. Wave propagation issues and their physical interpretations pertinent to the modeling of assorted terrain conditions are presented within the scope of the following: (1) Demonstration of the relevancy and significance of various types of surface waves defining near-grazing radiowave interactions with a dielectrically-covered terrain through the derivation of second order asymptotic solutions. (2) Treatment of the diffraction effect of a vegetation layer discontinuity using Kirchhoff-Huygens approach and validation of obtained results with measurements from an experimental setup. (3) Simulation of long-distance propagation over undulating terrain surfaces with a high order numerical solver achieving accurate solutions with as few as one unknown per linear wavelength for highly rough profiles (rms slope up to 15°). (4) Characterization of ground wave propagation over random rough surfaces with closed-form effective, near-grazing reflection coefficients formulated from an existing volumetric polarization current-based perturbation approach. (5) Performance analysis and comparison of low-profile, near-ground radiating structures with a hybrid modeling technique.