Improvement of Oblique Incidence Performance for a Microwave Absorber Based on Magnetic Polymer Composites

摘要

This paper presents a microwave absorber combining together the frequency selective surfaces (FSSs) and magnetic absorbing sheet for stable absorption under both TE and TM polarizations. The proposed absorber is constructed of magnetic absorbing substrate embedded with a periodic array of cross pattern composing a series of circular-metal-disks, and a bottom metal plane. The absorption characteristics of the magnetic absorbing substrate under both TE and TM polarizations are tuned and improved by introducing the circular-metal-disks. After optimizing the dimensions of the circular-metal-disks, the absorber with a thickness of 2.4 mm achieves a reflection coefficient less than --10 dB from 4.8 GHz to 11.0 GHz with a stable frequency response up to 30° for both polarizations. Meanwhile, the absorber has a wide bandwidth of 10.8 GHz with the incidence angle from 45° to 60° under TM polarization. The study of the current indicates that the improvement of the absorption characteristics is due to both the electric resonance and magnetic resonance.