Near-Field Virtual Bandwidth Synthetic Aperture Radar Processing for Humanitarian Landmine Detection

Poster presented at the 2017 Defence and Security Doctoral Symposium.

This research presents the first experimental demonstration of the Near-Field Virtual Bandwidth SAR (NFVB-SAR) imaging technique. NFVB-SAR is a newly developed sub-surface imaging technique which in contrast to traditional imaging techniques promises subsurface imaging of soils at ultra-high, centimetre-scale resolution using narrow bandwidth. We specifically exploit the differential interferometric SAR phase history of an electromagnetic wave within a drying soil volume to generate high resolution sub-surface mapping from the returned wave through the soil volume. Experiments were conducted at the Cranfield University Antennas and Ground Based SAR (AGBSAR) laboratory using a near-field full polarimetric data acquisition ground penetrating radar. Measurements were taken over a sandy soil containing a buried landmine while the moisture level was varied. - firstly during controlled water addition and then during an extended natural drying out period. As the sand volume dries, the real radar frequency is sequentially transported across a virtual bandwidth of virtual frequencies. The preliminary results demonstrate that even a moderate soil moisture change (SMC) can produce large virtual bandwidths; for e.g. an SMC change of 10% can provide 6cm vertical resolution at X-band. We acknowledge the financial support of the Sir Bobby Charlton Charity "Find A Better Way".