Antenna Aperture Localization for Arrival Time Correction Using First-Break

For microwave imaging systems that utilize antennas with spatially separated feeds and apertures, arrival time correction based on the antenna aperture location is one of the fundamental steps in radar data processing. The estimates of the antenna aperture time and the corresponding average velocity in the material in contact with the antenna are expected to have a significant impact on the quality of the reconstructed image. In this paper, we propose antenna aperture and average velocity estimation by least-squares regression analysis of the first-breaks. The results indicate that the proposed method is able to process either the reflection data or the transmission data measured by antennas with different structures. Compared to those readily identifiable characteristics in the signal, the first-break is less influenced by waveform distortion and is able to provide more consistent reference. Differences in the images of test objects are also noted.