ON THE COMPARISON OF UWB ANTENNAS FOR GPR APPLICATIONS
Résumé
Two optimized antenna prototypes for the ground penetrating radar in [0.6 GHz 3GHz] frequency band are presented in this paper. Depth penetration is ensured by the lower frequency whereas centimetric vertical resolution is allowed by the higher one. The first prototype is a spiral antenna, built on FR-4 substrate (εr = 4.2), which has a wide band behavior and which can be easily designed. Nonetheless spiral antennas are known for being dispersive and presenting a bidirectional radiation pattern. Several solutions are provided to overcome these limitations. The second prototype is a Vivaldi antenna. The gradual curvature of the radiating structure ensures a wide bandwidth. The major difficulty is the design of the antenna feeding which has an influence on the pulse distortion in the time domain and on the matching properties of the antenna in the frequency domain.