An inspection of this figure reveals that the spectrum of PSS PhC templates measured at the incident angle of 10° exhibits a maximum reflection of 34% at the wavelength of 432 nm.
When the thickness is just 1.25 mm, the reflection loss values below −10 dB can be achieved from 13.8 to 18 GHz, with a maximum reflection loss of −25.9 at 16.1 GHz.
When the matching thickness is up to 2.0 mm, the bandwidth with the reflection loss of R-GO/SF/PANI-2 nanocomposite below −10 dB is up to 5.84 GHz at 9.88 10.32 GHz and 10.48 15.88 GHz, but the maximum reflection loss is −32.42 dB at 12.48 GHz.
By simply controlling annealing temperature, the hybrid nanowires annealed at 1300 °C present a maximum reflection loss (RL) of −22 dB at 16.8 GHz with a small thickness of 1.7 mm and an effective absorption bandwidth (RL < −10 dB, 90% EM wave absorption) covers from 8 to 18 GHz.
This shows that the thin film has maximum reflection point and is about at the 380 410 nm wavelength.
Bhattacharya et al. [48] prepared a 2 mm thick unmodified MWCNT/polyurethane nanocomposite at a 30 wt% CNT loading through solution blending using mechanical stirring, with the maximum reflection loss of 16.03 dB at 10.99 GHz.
The epoxy based nanocomposites exhibited semi-conductive behavior and a maximum reflection loss of −15.4 dB at 16.5 GHz were obtained with thin thickness (1.6 mm) and low particles loading (2 wt%) of specimen.
When 5 wt.% carbon black is blended with 50 wt.% SiC to fabricate a composite with a 2 mm thickness, the maximum reflection loss becomes −41 dB at 9 GHz, and the −10 dB bandwidth reaches 6 GHz.
Taking both the synergistic benefits of magnetic CoNi nanocrystals and electric nitrogen-doped graphene, the CoNi/nitrogen-doped graphene hybrids show a maximum reflection loss of −22 dB at 10 GHz with a matching thickness of only 2.0 mm, and the effective absorption bandwidth with reflection loss exceeding −10 dB is 3.6 18 GHz with the absorber thickness of 1.35 5.0 mm.
The results show that the rGO/porous Bi2Fe4O9 composite exhibits a maximum reflection coefficient of −71.88 dB at 13.8 GHz with a sample thickness of only 2.0 mm and an effective absorption bandwidth (reflection loss below −10 dB) of 4.24 GHz, greatly superior to the present graphene-based metallic oxide composite.
