The near-field processing and narrowband imaging algorithm for MIMO array
Purpose - Imaging is a really difficult problem when systems are implemented in the near-field region and real-time needs. The purpose of this paper is to consider a novel system model and present a nanowband 2-D imaging algorithm in the near-field region and under the real time constraint. Design/methodology/approach - The first part of this paper proposes a novel approximation for the round-trip distance of the near-field echoed data based on a 2-D synthetic aperture planar array. The second part of this work proposes a near-field narrow imaging algorithm based on the above system model. Narrowband waveforms are employed in the array system, so that the range alignment and decoupling in range-azimuth are not necessary. Findings - The errors of the proposed approximation are much smaller as compared with those of the Fresnel approximation. For example, the errors of the proposed approximation are negligible when the antenna is fixed at (0, 0). In other cases, the errors are decreased by almost 50 percent. Compared with 2-D plane array, the synthetic aperture plane of the paper reduces the number of antennas. Finally, numerical simulation results verify the validity of the imaging algorithm. Originality/value - The near-field difficulty is solved by the adoption of the proposed approximation. The theoretical analysis and simulation results verify the validity of the imaging algorithm in the near-field region and under the real time constraint.
near-field radar image processing radar imaging multiple-input multiple-output