Investigation on the aperture size for SAR focusing of subsurface targets

The influence of the antenna aperture size on the SAR focusing of subsurface targets is investigated in this contribution. Synthetic aperture focusing techniques are used in subsurface radar for enhancement of the lateral, i.e. the spatial resolution of the buried objects. In order to evaluate the effect of the aperture on the reconstructed image different standard gain horn antennas are applied at Ku-Band (12-18GHz). The antennas with varying apertures are used subsequently in a laboratory GPR setup in the same test scenario. An exact focusing technique that regards the refraction of the two-layered geometry is applied on the measured radar raw data. Since the applied aperture antennas do have different antenna gains, they exhibit different beamwidths and different Fresnel zones. The identification of subsurface targets is largely dependent on the beam that illuminates the area onto the ground surface. The experiment in a prepared GPR setup investigates the impact of the size of the real aperture on the synthetic aperture focusing technique.