Deminers around the globe are still using handheld metal detectors that lack the capability to distinguish mines from clutter, detect mines containing very little metal, or find mines buried at deeper depths. In the southern African country of Angola, many areas and roads are impassable due to the threat of anti-tank landmines. Some of these mines are undetectable using current metal detector technology. The US Army has funded the development of the NIITEK ground penetrating radar (GPR) for detection of anti-tank (AT) landmines. This radar detects metal and plastic mines as well as mines that are buried too deep for handheld metal detectors to find. The US Department of Defense Humanitarian Demining (HD) Research & Development Program focuses on developing, testing, demonstrating, and validating new technology for immediate use in humanitarian demining operations around the globe. The HD team provided funding and guidance to NIITEK Incorporated for development of a prototype system called Mine Stalker - a relatively light-weight, remote-controlled vehicle outfitted with the NIITEK GPR, detection algorithms, and a marking system. Individuals from the HD team, NIITEK Inc, and the non-governmental organization Meschen Gegen Minen (MgM) participated in a field evaluation of the Mine Stalker in Angola. The primary aim was to evaluate the effectiveness and reliability of the NIITEK GPR under field conditions. The Mine Stalker was extremely reliable during the evaluation with no significant maintenance issues. All AT mines used to verify GPR performance were detected, even when buried to depths as deep as 25-33cm.