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Computation of HF Ground Backscatter Amplitude
Author(s) -
Croft Thomas A.
Publication year - 1967
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1002/rds196727739
Subject(s) - backscatter (email) , ionosphere , scattering , earth's magnetic field , azimuth , computational physics , incoherent scatter , specular reflection , amplitude , radar , physics , range (aeronautics) , remote sensing , optics , geology , geophysics , computer science , magnetic field , telecommunications , materials science , composite material , quantum mechanics , wireless
An HF backscatter radar system is simulated by a digital computer method which includes the detailed influence of the ionosphere through use of precomputed rays. To insure a fairly realistic simulation, allowance is made for the following factors: a spherical earth and ionosphere, electron density variations with height and range, absorption which varies with range and ray angle, antenna gain as a function of azimuth and elevation, ground scattering and specular reflection characteristics which vary with range and angle of incidence, and the transmitted pulse shape. The main approximations are (a) that ray theory is used with the assumption that most energy is distributed uniformly between closely spaced ray paths, and (b) that the effect of the geomagnetic field on ray‐path range and transit time is neglected. This computer simulation has two main applications. First, it permits the study of idealized backscatter problems by controlled variation of one parameter at a time. For example, a localized irregularity may be inserted in the ionosphere and the backscatter can be calculated with and without it. Second, it is possible to match experimental backscatter with synthetic backscatter for the purpose of evaluating the ground‐scatter coefficient or estimating the existing ionospheric structure. This process requires carefully calibrated experimental data because the comparison must be quantitative. Some early results of this work are shown.