From the prevention of natural disasters such as landslide and avalanches, to the enhancement of energy efficiencies in chemical and civil engineering industries, understanding the collective dynamics of granular materials is a fundamental question that are closely related to our daily lives. Using a recently developed multi-static radar system operating at 10 GHz (X-band), we explore the possibility of tracking a projectile moving inside a granular medium, focusing on possible sources of uncertainties in the detection and reconstruction processes. On the one hand, particle tracking with continuous-wave radar provides an extremely high temporal resolution. On the other hand, there are still challenges in obtaining tracer trajectories accurately. We show that some of the challenges can be resolved through a correction of the IQ mismatch in the raw signals obtained. Consequently, the tracer trajectories can be obtained with sub-millimeter spatial resolution. Such an advance can not only shed light on radar particle tracking, but also on a wide range of scenarios where issues relevant to IQ mismatch arise.

中文翻译：

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用于弹丸撞击颗粒介质的雷达

从预防山体滑坡和雪崩等自然灾害，到提高化工和土木工程行业的能源效率，了解颗粒材料的集体动力学是与我们日常生活息息相关的基本问题。使用最近开发的在 10 GHz（X 波段）运行的多静态雷达系统，我们探索了跟踪在颗粒介质内移动的射弹的可能性，重点关注检测和重建过程中可能的不确定性来源。一方面，连续波雷达的粒子跟踪提供了极高的时间分辨率。另一方面，准确获取示踪轨迹仍然存在挑战。我们表明，可以通过校正获得的原始信号中的 IQ 不匹配来解决一些挑战。因此，可以以亚毫米空间分辨率获得示踪剂轨迹。这样的进步不仅可以揭示雷达粒子跟踪，还可以揭示出现与 IQ 失配相关的问题的广泛场景。