2D patterned magnetic composite sheets for polarization-insensitive and wide-angle microwave attenuation

Magnetic composite sheets loaded with carbonyl iron powders (CIP) are widely used due to their high-efficiency microwave attenuation at very thin thickness because of their outstanding permeability and magnetic loss. However, their performance varies dramatically at various incident angles and polarization modes, namely transverse electric (TE) and transverse magnetic (TM) modes. In this study, it is demonstrated that two-dimensional (2D) patterning could offer an effective solution for achieving wide-angle performance in both TE and TM modes. Different shapes of the 2D patterns (circles, hexagons, and cross-holes) are investigated and their dimensions are optimized through full-wave simulation. The consistent results with the experiment reveal that these 2D patterns with optimized dimensions could improve TM mode performance significantly to above 20 dB attenuation for an oblique incident angle up to about 40 degrees, thanks to the resulted field resonance revealed by simulation. Due to the improved TM mode performance, the patterned composite sheet could exhibit almost identical high-efficiency attenuation in both modes, becoming polarization-insensitive. The performance improvement also comes with a similar to 16% reduction in weight. Given these merits and the ease of fabrication, the low-profile and robust 2D patterned magnetic composite sheets could attract great attenuation in practical applications for wide-angle and polarization-insensitive microwave attenuation.