Towards Handheld Millimetre-Wave Scanners: Challenges and Opportunities of Freehand Imaging Systems

Freehand imaging systems enable the retrieval of high-resolution electromagnetic images with a compact handheld device. In particular, they rely on radar modules of reduced size that are moved by hand by the operator of the system over the area under inspection while its position is tracked. Thus, they bypass the use of bulky positioners and their overall cost is drastically reduced. This work summarizes the main features of these systems and their architecture, and provides an overview of the latest advances in this technology. In addition, some of the challenges that must be addressed to enable the use of freehand systems in practical applications, illustrated with measurements obtained with a freehand imaging prototype, are discussed.