Real-Time Millimeter-Wave Imaging for Moving Targets Realized in a Sparse Array Based on InP-HBT MMICs

Millimeter-wave (MMW) imaging has been widely studied for applications, such as personnel screening and industrial noninvasive testing; however, real-time MMW imaging with a subcentimeter resolution and a large field of view (FoV) for a fast-moving target has been rarely reported to date. In this article, we present the design of such an imaging system at the $Ka$ -band utilizing the concept of multistatic sparse array. Microwave monolithic integrated circuits based on an InP-heterojunction bipolar transistor (HBT) technology are used for the transmitter and receiver chipsets. With the help of an improved backprojection algorithm and a computation platform based on field-programmable gate arrays, real-time imaging for a target moving as fast as about 10 m/s is demonstrated at a frame rate of over 20 frames/s. The imaging resolution is measured to be better than 6 mm and the FoV can reach over $1\times 1\,\,\text{m}^{2}$ . Imaging of a moving person with concealed items is carried out to illustrate the system's capability for personnel screening. To the best of the authors' knowledge, this is the first real-time MMW sparse array imaging system built upon InP-HBT chipsets.