An existing forward-backward time-stepping (FBTS) time-domain quantitative imaging algorithm is augmented with a discontinuous Galerkin method (DGM) forward solver. The resulting DGM-FBTS imaging algorithm is capable of solving the electromagnetic inverse scattering problem using high-order expansions of the fields and unknown target constitutives, decoupling the solution from the unstructured grid. DGM-FBTS provides a time-domain alternative to our previous development of flexible DGM-based frequency-domain imaging codes, and enables us to present a comparison of the performance of time-domain and frequency-domain imaging algorithms for synthetic and experimental targets. For experimental targets, a procedure for obtaining calibrated time-domain data from frequency-domain broadband VNA-collected data is explained and applied to a system with a reduced number of transmitters and receivers to highlight the potential benefits of time-domain methods. Results highlight the potential capabilities of time-domain experimental imaging using the same hardware configuration used to collect broadband frequency-domain measurements and suggest future work on hybrid frequency- and time-domain imaging algorithms and efforts to improve the computational performance of DGM-FBTS.

中文翻译：

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实验目标时域和频域微波成像的比较


现有的前向-后向时间步进 (FBTS) 时域定量成像算法通过不连续伽辽金法 (DGM) 前向求解器进行了增强。由此产生的 DGM-FBTS 成像算法能够使用场的高阶展开和未知目标构成来解决电磁逆散射问题，从而将解决方案与非结构化网格解耦。 DGM-FBTS 为我们之前开发的基于 DGM 的灵活频域成像代码提供了时域替代方案，并使我们能够对合成目标和实验目标的时域和频域成像算法的性能进行比较。对于实验目标，解释了从频域宽带 VNA 收集的数据获取校准时域数据的过程，并将其应用于发射机和接收机数量减少的系统，以突出时域方法的潜在优势。结果突出了使用用于收集宽带频域测量的相同硬件配置进行时域实验成像的潜在能力，并建议未来在混合频域和时域成像算法方面的工作以及提高 DGM-FBTS 计算性能的努力。