Eliminating Ghost Phantoms in Computational Microwave Imaging by Breaking Receiver Symmetry

This paper addresses the challenge of eliminating ghost phantoms in frequency-diverse computational microwave imaging (CMI) by optimizing the arrangement of receiving antennas. Ghost phantoms, usually refer to unreal objects that appear in reconstructed images, can cause significant challenges. These ghost phantoms are primarily attributed to factors such as system inaccuracies, deficiencies in signal processing and the intricate electromagnetic phenomena present in the environment. Traditional approaches to address this issue in CMI focus on enhancing signal processing algorithms or increasing the diversity of measurement modes. In this work, we present that the intrinsic symmetry in the arrangement of transmitter (Tx) and receiver (Rx) components of a CMI system also substantially contributes to the occurrence of these ghost phantoms in reconstructions. We propose a solution by breaking the symmetry in the Rx configuration to reduce the ghost phantom occurrence in the reconstructed images. We use full-wave simulations to investigate the effects of three different receiver arrangement schemes on image reconstruction: uniform, half-uniform and half-irregular, and fully irregular. The results demonstrate that breaking the symmetry of the Rx elements, particularly by adopting an irregular arrangement, significantly improves the quality of the reconstructed images.