1：Experimental Design and Method Selection:

The study involved the fabrication of a carbon fiber reinforced flexible thin hierarchical metastructure (HM) using a combination of vacuum bag techniques and hand lay-up methods. The lossy material was composed of spherical carbonyl iron (CI), multiwall carbon nanotube (MWCNT), and silicone rubber (SR). Twelve concentrations of the materials were fabricated to investigate their effects on electromagnetic parameter combination. Multi-scale optimization on material and structural levels was applied to achieve improved microwave-absorbing and mechanical performance.

2：Sample Selection and Data Sources:

The MWCNT was purchased from Shenzhen Nanotech Port Co. Ltd., China, and the spherical CI particles were supplied by Shanxi Xinghua Co. Ltd., China. The platinum-catalyzed liquid silicone rubber (LSR) Ecoflex 0030 was purchased from Smooth-on Inc., USA. The plain weave CF cloth was supplied by Weihai Guangwei Composites Co. Ltd.

3：List of Experimental Equipment and Materials:

The study utilized a field emission scanning electron microscope (Quanta 450 FEG, FEI), a vector network analyzer (VNA, Ceyear AV3672D), and a universal testing machine (Instron Legend 2367).

4：7). Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: The composite was fabricated in rectangular shapes following the standard waveguide method. The mixture was poured into polytetrafluoroethylene moulds to be cured in vacuum at 70℃ for 2 hours. The CF reinforced HM was fabricated by pouring the liquid mixture into a female acrylic mould and then applying CF layers with LSR.

5：Data Analysis Methods:

The complex permittivity and permeability of the composites were measured with the two-port waveguide connected to the VNA. The reflectivity of the shaped HM was measured with the NRL arch method. The mechanical properties were characterized to obtain stress-strain curves, Young’s modulus, and fracture strength.