| 摘要 |
An electromagnetic signal having originally the time variation of a rectangular pulse is radiated into a lossy medium with conductivity sigma . It is distorted by the medium to the distorted electromagnetic pulse f( sigma ,y,t) when it travels the distance y/2, in time t/2, from a transmitter to a scattering or reflecting target and the same distance y/2, in time t/2, back to the receiver. The time variation f( sigma ,y,t) of the distorted pulse can be calculated for any conductivity sigma and distance y using the conductivity sigma known from previous measurements to determine the range to the target distorted pulse f( sigma ,y,t). Consequently, distorted pulses f( sigma ,yn,t) can be computed and compared to the received distorted pulse f( sigma ,y,t). The computed pulse f( sigma ,yn, t) that is most similar to the received pulse f( sigma ,y,t) determines the distance yn/2 to the scattering or reflecting object, which is the range to the target. The comparison between the computed, distorted signals and the actually received signal can be done by cross-correlation. If cross-correlation is used, the peak amplitude or the energy of the received signal becomes unimportant which means the physical size or radar cross-section of the target has no effect on the distance determination.
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