The frequency shift of a pulse by a time-independent, dispersive, lossy medium
Abstract
A pulse undergoes a frequency shift while propagating through a medium whose losses depend on frequency. The amount of the frequency shift is proportional to the imaginary part of the complex group refractive index and the distance traveled in the medium. No new frequencies are generated that were not in the original signal; the signal energy is merely 'redistributed' by selective absorption. In an inhomogeneous medium, the frequency shift is proportional to the imaginary part of the complex group path. Furthermore, a beam propagating in a medium where the losses depend on the direction of propagation will be bent toward the direction of least attenuation. Again, no components in the angular spectrum are generated that were not in the original beam. The signal energy is merely redistributed by selective absorption.
- Publication:
-
NASA STI/Recon Technical Report N
- Pub Date:
- September 1981
- Bibcode:
- 1981STIN...8228542J
- Keywords:
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- Frequency Shift;
- Lossy Media;
- Pulsed Radiation;
- Time Dependence;
- Angular Distribution;
- Radiation Absorption;
- Wave Attenuation;
- Wave Propagation;
- Communications and Radar