Radio Science

Backscattering of wideband signals from turbulent slabs


  • George C. Valley


The traditional first Born approximation cross section for scattering of electromagnetic radiation by turbulent irregularities is generalized to include the effect of an arbitrarily modulated signal incident on the irregularities and the effect of cutting off the volume of the irregularities in the direction of propagation with an arbitrary function. This generalized cross section is proportional to a double convolution integral over the frequency spectrum of the incident signal, the spectrum of the turbulent irregularities, and the square of the Fourier transform of the function which cuts off the irregularities. Analytic and numerical results are given for the ratio of this generalized cross section to the traditional cross section for gaussian and rectangular slabs and for gaussian and rectangular pulses combined with several different turbulence spectra. The results show how the generalized cross section mixes Fresnel reflections with turbulent reflections and wideband scattering with scattering at twice the carrier frequency.