Page 143 - MSAM-4-3

Materials Science in Additive Manufacturing Sunflower-inspired microwave-absorbing metastructure

A B

Figure 10. Absorption spectra of the sunflower-inspired metastructure under various incident angles and polarization states. (A) Reflection loss (RL)
under transverse electric polarization for incident angles 0 – 60°. (B) RL under transverse magnetic polarization

Figure 11. Polarization dependence of the sunflower-inspired metastructure, showing RL as a function of polarization angle and demonstrating
polarization insensitivity
Abbreviations: TE: Transverse electric; TM: Transverse magnetic; RL: Reflection loss
peak frequency (4.66 GHz), the electric field mainly at the top edge by 17.04 GHz with strong energy dissipation
concentrates on the upper edges and inter-unit gaps, at the structure’s boundary, consistent with high-frequency
whereas the magnetic field localizes near the bottom metal edge diffraction effects.
plane, demonstrating a classic λ/4 resonance behavior. 36-38 In summary, the sunflower-inspired metastructure
At the second peak (8.80 GHz), the electric field extends achieved microwave attenuation through multiple
to the top structure and across interlayer gaps, whereas mechanisms:
the magnetic field shifts to the middle and lower sections • Low frequencies: λ/4 resonance induced by magnetic
of the absorber. By the third peak (13.25 GHz), a strong losses near the metal backplane;
structural resonance appears between adjacent units, and • Intermediate frequencies: structural resonance
the magnetic field shifts toward the top center. At the between adjacent spiral layers;
fourth peak (17.04 GHz), both electric and magnetic fields • High frequencies: edge diffraction and strong field
are concentrated near the top edge, exhibiting pronounced localization at the structure’s periphery.
edge diffraction effects. 39,40
The correlation between the magnetic field and power
Figure 13 presents the power loss density distributions loss distributions at high frequencies also suggests that
at the same frequencies. At 4.66 GHz, energy loss is magnetic losses, such as those caused by domain wall
concentrated in the central region of the metastructure. As motion and hysteresis between adjacent structural units,
frequency increases, the loss region gradually shifts toward are significant contributors to microwave absorption in the
the top and eventually to the top edge. The loss culminates designed metastructure.

Volume 4 Issue 3 (2025) 9 doi: 10.36922/MSAM025220048