Multi-channel GPR

Abstract

Advances in ground penetrating radar imaging with multi-channel systems have greatly improved the speed and areal coverage for archaeological prospection. Even though the first introductions of multi-channel GPR systems and designs date back more than two decades (e.g. Warhus et al. 1993; Anderson et al. 1991), the complete acceptance of multi-channel recording was limited by the quality of the data and complex data processing (Francese et al. 2009). Differences in the frequency responses and directional responses of similarly manufactured antenna elements as well as cross talking between elements proved to be problematic. Individually, the channels would often look very good but collectively these early systems were not balanced enough between the different elements to work effectively as a multi-channel array. However, in recent years, most of the multi-channel manufacturers have provided GPR systems where the antenna responses of the individual elements are very similar (Linford et al. 2010; Trinks et al. 2010ab; Simi et al. 2010). With the cross-line spacing between adjacent antenna approaching a 1/4 wavelength of the transmitted microwaves into the ground, multi-channel systems have the advantage of complete coverage of a site (Grasmueck et al. 2004; Novo et al. 2008) allowing for full resolution imaging. Multi-channel systems can best be defined as full resolution GPR systems when crossline separation of the antenna approach the 1/4 wavelength of the transmit pulses in the ground (Annan 2009). With density on the ground at a 1/4 wavelength or better, interpolation to generate 3D volume of continuous GPR pulses collected on a site is not required except to fill in the gaps between adjacent tracks if so desired (Goodman et al. 2011).