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IEEE Transactions on Antennas and Propagation
Volume 48 Number 5, May 2000

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A Novel Finite-Difference Time-Domain Wave Propagator

Funda Akleman and Levent Sevgi

Page 839.

Abstract:

In this letter, a novel time-domain wave propagator is introduced. A two-dimensional (2-D) finite-difference time-domain (FDTD) algorithm is used to analyze ground wave propagation characteristics. Assuming an azimuthal symmetry, surface, and/or elevated ducts are represented via transverse and/or longitudinal refractivity and boundary perturbations in 2-D space. The 2-D FDTD space extends from x=0 (bottom) to x -> (top), vertically and from z -> - (left) to z -> (right), horizontally. Perfectly matched layer (PML) blocks on the left, right, and top terminate the FDTD computation space to simulate semi-open propagation region. The ground at the bottom is simulated either as a perfectly electrical conductor (PEC) or as a lossy second medium. A desired,initial vertical field profile, which has a pulse character in time, is injected into the FDTD computation space. The PML blocks absorb field components that propagate towards left and top. The ground wave components (i.e., the direct,ground-reflected and surface waves) are traced longitudinally toward the right. The longitudinal propagation region is covered by a finite-sized FDTD computation space as if the space slides from left to right until the pulse propagates to a desired range. Transverse or longitudinal field profiles are obtained by accumulating the time-domain response at each altitude or range and by applying discrete Fourier transformation (DFT) at various frequencies.

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