Near-Field Radar Imaging Using MMIC-Based Large-Aperture Array

A sparse large-aperture imaging radar system based on highly integrated monolithic microwave integrated circuits (MMICs) is introduced in this article. The integration of additional functionalities onto MMICs serves to eliminate the need for costly substrates and complex off-chip feedlines. The entire imaging array follows a quasi-coherent setup, divided into independent MMICs, with a sparse MMIC distribution for a larger aperture. To address near-field effects and grating lobes, a novel near-field imaging method based on an adaptive weighting technique is proposed. This approach employs optimized weights to calibrate amplitude and phase errors while suppressing the grating lobe through sum and difference image cancellation. An experimental prototype with an azimuth resolution of 0.85° demonstrated significant improvement in imaging performance, validating the proposed algorithm.