N.A. Cartwright and K.E. Oughstun (USA)
wave penetration, ultrawideband pulse propagation, pre cursors
The high frequency, low power characteristics of ultra wideband/short-pulse signals exhibit uniquely promising features with applications to remote sensing of terrestrial objects from satellites, foliage-penetrating radar, as well as the study of biological tissue exposed to ultrawideband pulses. Indeed, previous studies of ultrawideband elec tromagnetic pulse propagation through dispersive, noncon ducting media has shown the existence of a so-called Bril louin precursor whose peak amplitude only decays alge braically with propagation distance. However, materials such as the ionosphere, foliage and biological tissue ex hibit conductivity. In this paper, we show that a Debye model material with static conductivity does indeed support a Brillouin precursor, but that this precursor now attenu ates exponentially with propagation distance and not just algebraically. Nevertheless, we show that it is still advan tageous to track the Brillouin precursor in remote sensing applications because its attenuation is less than the attenu ation of the main signal.
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