Sparse cross array that operating in the 90~94GHz frequency band was designed for the handheld millimeter-wave human body security inspection. The time-domain correlation algorithm and the modified range migration algorithm (RMA) were chosen as image reconstruction methods. Due to the existence of spherical wave expansion approximation and complex interpolation processes in the deriving of the modified RMA algorithm

a high-precision FFT-based imaging algorithm without spherical wave expansion and complex interpolations was proposed. The electromagnetic simulation software was used to build target model obtaining raw echo data

the resolution test and noise robustness verification experiments were carried out. The azimuth resolution can achieve 5mm

which meets the system design requirements

and verifies the effectiveness of the proposed algorithm. The computational efficiency of the proposed algorithm is better than that of the time-domain correlation algorithm and the noise robustness is better than the modified RMA algorithm. It can be concluded that the proposed algorithm is a better choice in real-time imaging scenarios of the handheld millimeter-wave human body security inspection.