Fig 1

EM parameters required for effective absorption at different frequency bands and coating thicknesses: (a) schematic illustration of the transmission line theory calculation model, (b) isosurface of RL = −10.0 dB with μr = 1.0 and coating thickness of 2.0 mm, (c) RL values at different frequencies with μr = 1.0 and coating thickness of 2.0 mm, (d) EM wavelength distribution that satisfies RL = −10.0 dB under different frequencies and εr with the coating thickness of 2.0 mm (around λ = 4d), (e) contour line of RL = −10.0 dB at 2.0–5.0 GHz with μr = 1.0 and coating thickness of 2.0 mm, (f) contour line of RL = −10.0 dB at 6.0–18.0 GHz with μr = 1.0 and coating thickness of 2.0 mm, (g) isosurface of RL = −10.0 dB with μr of magnetic F-CIPs and coating thickness of 2.0 mm, (h) contour line of RL = −10.0 dB at 4.0–8.0 GHz with μr of magnetic F-CIPs and coating thickness of 2.0 mm, (i) contour line of RL = −10.0 dB at 2.0–4.0 GHz with μr of magnetic F-CIPs and coating thickness of 4.0 mm."

Fig 2

CST simulation for different microstructures: (a) Schematic illustration of the polarization process under electric field; models of (b) blocks, (c) flakes, and (d) foam. (e) Volume filling amount, and (f) areas per unit volume of different models; (g) εr', and (h) εr'' values of different models."

Fig 3

Characterization of FeCo cubes, FeCo particles, and FeCo foam: (a) schematic illustration of preparing the FeCo foam, SEM image (b) FeCo oxide foam precursor, and (c) FeCo foam, (d) TEM image of FeCo foam and the corresponding element mapping images, (e) XRD patterns, (f) Mercury intrusion curves, (g) corresponding pore size diameter distribution curves, (h) total pore areas and (i) porosity of FeCo cubes, FeCo particles, and FeCo foam, (j) Component contents of FeCo cubes, FeCo particles, and FeCo foam."

Fig 4

Dielectric properties of FeCo cubes, FeCo particles, and FeCo foam: (a) εr', (b) εr'', (c) tanδe, (d) εc'', (e) εp'', and (f) Cole-Cole semicircles."

Fig 5

Magnetic properties of FeCo cubes, FeCo particles, and FeCo foam: (a) Magnetic hysteresis loops, and (b) their local magnification of FeCo cubes, FeCo particles, and FeCo foam, (c) Derivative of the demagnetization curve of FeCo cubes, FeCo particles, and FeCo foam, (d) Magnetic hysteresis loops of Fe foam, Co foam and FeCo foam, (e) μr', (f) μr'', (g) tanδm, and (h) C0 values of FeCo cubes, FeCo particles, and FeCo foam."

Fig 6

EM wave absorption performance and attenuation mechanisms of FeCo cubes, FeCo particles, and FeCo foam. Planar RL maps of (a) FeCo foam, (b) FeCo particles, and (c) FeCo cubes; (d) RL curves of FeCo foam with the coating thickness of 1.0 mm, 2.0 mm and 4.0 mm; (e) schematic illustration of an incident EM wave on EWAMs backed with a metal plate; (f) Front-face reflection coefficient values of FeCo cubes, FeCo particles, and FeCo foam; The separation of EM loss and λ/4 cancellation of FeCo foam with coating thicknesses of (g) 4.0 mm, (h) 2.0 mm, and (i) 1.0 mm."

Fig 7

RCS simulation and EM wave absorption performance of FeCo foam-based structures: (a) Models of PEC layer and EWAMs for RCS simulation, (b) RCS simulated curves of PEC layer and PEC layer coated with FeCo foam at different frequencies, (c) RCS reduction values and corresponding total energy loss of FeCo foam at different frequencies, (d) 3D RCS plot for PEC layer, and (e) PEC layer coated with FeCo foam with the coating thickness of 2.0 mm, (f) RCS simulated curves of PEC layer and PEC layer coated with FeCo foam from different scanning angles, (g) Model of multi-layer periodic structure and (h) its local magnification, (i) RL values of multi-layer periodic structure."