Detection of deep buried metal objects with the UltraTEM

Abstract

The UltraTEM Deep metal detection system combines a rugged, fast-switching transmitter with a powerful custom designed generator and one to ten three-component receiver coils that collect time-domain electromagnetic induction data across a wide time-range. The roving receiver is operated inside a fixed loop of copper cable, typically 30-150 m long and 5-50 m wide. The large size of the loop results in a slow falloff in primary field with depth and effective excitation of deep buried unexploded ordnance as well as other metal objects such as Ground Engaging Tools (GET). We describe the results of an extensive trial of the UltraTEM system at a magnetically challenging site in Laos. The UltraTEM was able to detect all seeded items buried at depths down to 5 m across a wide range of site conditions. Subsequent work with the system at a different site demonstrated an ability to detect GET to depths of at least 3.0 m in a magnetite stockpile.