Determination of the ice dielectric permittivity using the data of the test in Antarctica of the ground-penetrating radar for Mars'98 mission

A ground-penetrating radar will be integrated inside the guiderope ballast of the Mars'98 balloon mission. A prototype of this impulse system working in the 5-15 MHz band was tested close to Dumont d'Urville, the French Antarctic Station, in February 1993. The authors obtained a large set of profiles in cold ice with a glacier thickness from 200 to about 900 m. For each depth, the measured echoes are very clear with a good signal-to-noise ratio (SNR). In this paper, the authors firstly describe the performances of the radar and they study the electromagnetic propagation in the Antarctica glacier. This knowledge allows them to use the frequency wavenumber migration to focus the signal, to increase the SNR and to rebuild an image of the subsurface. The migration process gives a good estimation of the real part of the permittivity (i.e., the velocity). The fact that the signal comes from different depths is used to measure the imaginary part of the permittivity which defines the ice attenuation. The spectral analysis gives its frequency dependence.