Abstract This study introduces a fused filament fabrication (FFF) process for manufacturing complex-structured asteroid analogue objects to be applied in tomographic microwave radar measurements and inversion studies. We describe an approach to control the volume fraction of the plastic and, thereby, the effective relative permittivity within a tetrahedral wireframe which serves as metamaterial representing the actual asteroid composition. To determine the effective permittivity of the plastic–air mixture, we use an exponential model. In this study, two analogue objects based on the shape of the asteroids 1998 KY26 and (25143) Itokawa were 3D-printed in a scale suitable for microwave laboratory measurements using ABS filament with a controlled constant relative electric permittivity. The results obtained suggest that the permittivity of solid and powdery asteroid minerals can be modelled with the proposed technique and, in particular, that the numerical structural permittivity models of the earlier numerical studies can be approximated by 3D-printed analogues.

中文翻译：

---

复杂结构的 3D 打印线框作为层析微波雷达测量的小行星类似物

摘要 本研究介绍了一种用于制造复杂结构小行星模拟物体的熔丝制造 (FFF) 工艺，该工艺将应用于层析微波雷达测量和反演研究。我们描述了一种控制塑料体积分数的方法，从而控制四面体线框内的有效相对介电常数，该线框用作代表实际小行星成分的超材料。为了确定塑料-空气混合物的有效介电常数，我们使用指数模型。在这项研究中，两个基于小行星 1998 KY26 和 (25143) Itokawa 形状的模拟物体使用具有受控恒定相对介电常数的 ABS 灯丝以适合微波实验室测量的比例进行 3D 打印。