The Ground Penetrating Radar (GPR) WISDOM is designed to be part of 2018 ExoMars Rover payload. The main scientific objective of WISDOM is to characterize the material distribution within the first few meters of the Martian subsurface and to search for evidence of past and present life on Mars. The WISDOM radar will provide a penetration depth of about 3 meters with a resolution of a few centimetres within the Martian soil. A preliminary "real time" subsurface analysis supports the drill operations in finding places of high scientific interest and low risk. The joint data interpretation together with the drill team will significantly support the radar calibration. This presentation will focus on instrument performance depending on the accommodation of the WIDOM antennas aboard a Mars rover. Preliminary tests in the lab and in the field have shown that apart from the electronic unit the fully polarimetric antenna arrangement is one key element for the localization and characterization of buried scatterers and for the construction of a three dimensional subsurface map of the shallow Martian ground.