  The ExoMars mission of the program Aurora (ESA) aims to send a vehicle
(Rover) on Mars in 2013. Beyond the technological aspects of the mission, the
Rover will also carry scientific instruments for the analysis of Mars
subsurface to search traces of past or present life in the Martian soil. The
Rover will embark a drilling machine which will give access to samples of
sub-surface of Mars to 2 meters depth. This constitutes the great originality
of ExoMars, because the Mars sub-surface remains still unknown and seems to be
the best place to shelter good conditions to create life. This drilling machine
will be guided by a radar system sounder UHF, the WISDOM instrument, which will
also make possible to probe the Mars sub-surface to a few meters of depth to
detect water and to study the geological structures. We have analytical and
numerical electromagnetic models to simulate the behavior of an electromagnetic
wave in the Mars sub-surface, but also to simulate the interactions between the
wave and the structure of the Rover. The objective of the work which we present
consists in the study of the factors able to create disturbances of
measurements in order to correct the effects on the measured signal. Initially
we present the solution which we retained in order to be able during the same
calculation to simulate the displacement of the Rover on several tens of
meters. We also present the results relating to the effect of the orientation
of the antenna during displacement due to topography of the observation site.
