This paper focuses on an ef?cient approach of designing multi-static arrays for millimeter-wave imaging, based on the k-space or Fourier-spatial domain characteristic of imaging systems. Our goal is to decrease the redundancy of the data measured by each antenna, and to improve the resolution of the reconstructed image. The proposed technique is based on determining the role of each transmitter and receiver, in collecting the data from each voxel of the target in k-space domain and then rotating transmitters' beams to measure the desirable information. The effect of non-uniform redundant k-space domain frequency samples that act as an undesirable ?lter, is compensated using a modi?ed SAR back-projection algorithm. Experimental and simulation results are presented and compared with that of a sparse multi-static array with the same number of transmitters and receivers. Our simulations and measurements show signi?cant improvement in terms of overall quality and edge preservation in the reconstructed images. Also, the obtained results demonstrate that using the proposed structure and algorithm, the average improvement in peak-signalto-noise ratio (PSNR), structural similarity index measure (SSIM) and digital image correlation (DIC) metrics of 3.03 dB, 0.22 and 0.173, are achieved, respectively.

In this study, a thorough analysis of image reconstruction in an active millimetre‐wave (MMW) cylindrical imaging system is performed. To improve the system's performance in terms of the total cost as well as the coupling effect, sparse multi‐static arrays are desired. Nevertheless, the existing reconstruction methods fail to operate in sparse multi‐static antenna‐array systems. Therefore, to address these shortcomings, in this study, at first, the existing MMW mono‐static cylindrical image reconstruction methods are modified in both single‐frequency and wideband reconstruction platforms. Moreover, in order to further improve the image quality and the system cost, a sparse multi‐static one‐dimensional antenna array has been proposed. To use this sparse array in the cylindrical MMW imaging system, a novel multi‐static cylindrical image reconstruction method is also proposed. The performances of the proposed reconstruction methods for both mono‐static and sparse multi‐static cylindrical imaging structures are validated through numerical simulations. Through the obtained results, 83% reduction in antenna array cost along with a 25 dB decrease in coupling effect is achieved at the cost of a minor reduction in the reconstructed image quality.