Computational aspects of EM pulse propagation along the nonuniform earth surface are considered. For ultrawide-band pulses without carrier, the exact wave equation in a narrow vicinity of the wave front is reduced to a time-domain version of the Leontovich- Fock parabolic equation. To solve it by finite differences, we introduce a time-domain analog of the impedance BC and a nonlocal BC of transparency. Numerical examples are given to demonstrate the influence of soil conductivity on the received pulse waveform.
For a high-frequency modulated EM pulse, we develop an asymptotic approach based on the ray structure of the monochromatic wave field calculated at the carrier frequency. As an example, a problem of target altitude determination from overland radar data is considered.
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