UWB Vivaldi Antenna Array Lower Band Improvement for Ground Penetrating Radar Applications

This paper concerns a ground penetrating radar system (GPR) presenting beam forming ability. This ability is due to a great flexibility in the emission of wavefronts. The innovative concept is to use an array of antennas which can reconfigure itself dynamically, in order to focus on a desired target. This antennas system can act as a new microwave sensor to detect and characterize buried targets in an inhomogeneous medium which is the case study in various application fields such as geophysics, medical, planetology… Its electronics are in development with the DORT (Time reversal technique) method integration for optimizing the localization of buried target. This paper aims are to present the antenna optimization used in the GPR applications. Typical antennas used in GPR are generally Vivaldi ones directly on the ground. Especially, in the context of the space mission ExoMars 2020, the radar antenna is set on a mobile station at a distance of about 30 cm from the ground to avoid any contact. However, they are limited by their important size, due to the lowest frequency of their bandwidth. Results of this work concern an increase of the antenna bandwidth by shifting the lower-band limit, making it a UWB type [500 MHz - 4 GHz] without changing its size. As low frequency waves can spread deeper into probed medium, this optimization can improve the radar data inversion performances

Wisdom GPR measurements in a cold artificial and controlled environment

International audienceThe WISDOM (500MHz - 3GHz) GPR is one of the instruments that have been selected as part of the Pasteur payload of ESA's 2018 ExoMars Rover mission. One of the main scientific objectives of the mission is to characterize the nature of the shallow sub-surface on Mars and WISDOM has been designed to explore the first ∼ 3 meters of the sub-surface with a vertical resolution of a few centimetres. In order to illustrate and quantify the WISDOM performance, measurements in cold artificial and controlled conditions have been performed by the prototype. The objectives of this experiment were the detection of home made internal layering and the possible detection of a wedge included in the permafrost filled with different material with known characteristics. Some results and comparisons with a simple simulation are presented here and show the WISDOM performances