Dual Frequency Processing of Subsampled Measurements in W-band

Nowadays, mm-waves are targeted for numerous applications, among which security ones. With the increasing threats of attacks all over the world, concealed objects detection has become a major concern. Systems already exist but they need to be improved for the upcoming requirement of imaging a moving crowd. Having a real-time image is one of the serious challenges for system’s completion. Measurement time is an issue that we endeavor to drastically reduce. We image an object with subsampled measurements and the real-time back-propagation algorithm (BPA). The on measurements points compression rate is 95%. BPA intrinsically requires a high number of spatial measurements points to avoid grating lobes in the image, which makes the subsampling impracticable. We make use of a dual frequency processing to overcome this difficulty. The processing was tested on measurements taken at 77 and 94 GHz and results show a good grating lobe suppression. Few years ago, the practical implementation of this dual frequency technique would have been an issue but the increasing developments of systems at mm-Waves makes it easier.