A.V. Popov – Dr.Sc.(Phys.-Math.), Main Research Scientist, Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation of RAS E-mail: popov@izmiran.ru

I.V. Prokopovich – Research Scientist, Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation of RAS

E-mail: prokop@izmiran.ru

D.E. Edemsky – Ph.D.(Eng.), Senior Research Scientist, Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation of RAS

E-mail: deedemsky@gmail.com

P.A. Morozov – Ph.D.(Phys.-Math.), Senior Research Scientist, Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation of RAS

E-mail: pmoroz5@yandex.ru

A.I. Berkut – Dr.Sc.(Eng.), General Director of JSC VNIISMI (Moscow) E-mail: lozaberk@yandex.ru

We describe the principles of penetration depth enhancement implemented in Loza GPR series, allowing one to use GPR for the purpose of geological investigation. The examples of experimental deep GPR radargrams with specific protracted low-frequency reflections are given. An approximate solution of the 1D radio wave propagation problem, based on the coupled-wave method, is considered. It can serve as an efficient engineering tool for the estimation of the dielectric permittivity of the non-uniform subsurface medium. It was shown by model calculations that the received low-frequency signals can be explained by partial reflections from smooth gradients of the subsurface medium. In the framework of the applied approximation, an inverse problem solution is given.

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