Preliminary field results of an ultra-wideband (10-620 MHz) stepped-frequency ground penetrating radar

The authors present the results from preliminary field trials using a newly developed ultra-wideband, stepped-frequency ground penetrating radar system. This system has been developed to improve the maximum penetration depth capability in ground penetrating radar (GPR) applications without degradation of resolving power. To achieve this, they have based their system on the stepped-frequency radar technique operating across the 10-620 MHz frequency band. The stepped-frequency technique offers substantial benefits over existing time-domain (impulse) GPR systems. The main advantage of the technique is that it is relatively easy with current technologies to efficiently sample ultra-wideband signals with low speed analog-to-digital converters. Also, due to transmission of long duration waveforms, a high average transmitted power is much easier to obtain than for short-pulse and impulse waveforms. The stepped-frequency technique offers other potential advantages for GPR such as a variable dwell time on each frequency, and more flexibility in signal processing such as the ability to correct for system errors. Their system can operate over multi-octave bands within the 10-620 MHz frequency range. The radar has the capability to employ a short range gate (~10 ns duration) at each frequency step which can suppress unwanted strong signals (e.g. direct wave between antennas) relative to weak reflections from deep targets. Field trials of the radar have demonstrated the effectiveness of gating and of the system as a whole