A.S. Kryukovsky, I.V. Zaichiсkov

Mathematical numerical modeling of amplitude structures of the radiopulses propagating in homogeneous ionospheric plasma is fulfilled. Changes of radiopulse thin structures depending on plasma frequency, distance up to a source of radiation and width of a signal had been investigate by the methods of the space - time geometrical theory of diffraction. Numerical comparison non-uniform and uniform asymptotics, containing Fresnel and Bessel functions is executed. Is established, that the sizes of a vicinity of a light cone, where the application of a uniform asymptotic as Bessel function is necessary are rather insignificant. Inapplicability of parabolic approximation for study of thin radiopulses structures is shown.