Page 142 - MSAM-4-3

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

A B

C D

Figure 8. Effects of individual layer thickness on the absorption performance of the sunflower-inspired metastructure: (A) h , (B) h , (C) h , and (D) h
1 2 3 4
Figure 9. For effective absorption, Z should closely match
eff
the impedance of free space, i.e., the real part should be
close to 1, and the imaginary part close to 0. This condition
is generally met above 3.93 GHz. However, in the 2 – 3.93
GHz range, both the real and imaginary parts fluctuate,
indicating impedance mismatch and reduced absorption
efficiency at low frequencies.
To further explore the metastructure’s angular and
polarization stabilities, RL was simulated under varying
incident angles for both transverse electric (TE) and
transverse magnetic (TM) polarizations. As shown in
Figure 10, the metastructure maintains robust absorption
performance across a range of incident angles. Under
TE polarization, the EAB (RL < −10 dB) remains nearly
unchanged up to 33°, due to enhanced multiple reflections
and edge scattering between adjacent units. 34,35 Beyond
33°, the bandwidth gradually decreases as more waves Figure 9. Real (Z ’) and imaginary (Z ’’) parts of the equivalent input
are reflected at higher incident angles. TM polarization impedance (Z ) for the sunflower-inspired metastructure as a function of
eff
eff
eff
demonstrates greater angular stability. Even at 50°, the frequency, illustrating the impedance matching behavior with free space
EABs for TE and TM waves remain as high as 10.63 GHz
and 13.70 GHz, respectively. The centrosymmetric design
of the metastructure unit also ensures polarization To elucidate the absorption mechanisms, electric
insensitivity, as confirmed by the consistent response at and magnetic field distributions were simulated at four
various polarization angles ranging from 0° (TE mode) to characteristic peak frequencies: 4.66 GHz, 8.80 GHz,
90° (TM mode) in Figure 11. 13.25 GHz, and 17.04 GHz (Figure 12). At the first

Volume 4 Issue 3 (2025) 8 doi: 10.36922/MSAM025220048