Microwave properties of the single-layer periodic structure composites composed of ethylene-vinyl acetate and polycrystalline iron fibers.

A single-layer microwave absorbing structure composed of the ethylene-vinyl acetate (EVA) powders and polycrystalline iron fibers (PIFs) with thickness of 2 mm, which has a periodic array of circular hole, is designed and fabricated using the mechanical method. We show that the reflection loss (RL) can be easily adjusted by changing the geometric parameters. The maximum RL is 18.7 dB at 15 GHz, and the effective absorption bandwidth of 1.7 GHz for the diameter of circular hole is 10 mm, and enhanced to be 23.7 dB at 15.1 GHz with the corresponding bandwidth of 7.2 GHz when the diameter decreases to 5 mm. The measured absorption of the composite is in good accordance with the simulation results. Furthermore, the possible absorption mechanism of the composite has been discussed. Our results illustrate that the integration of frequency selective surface (FSS) with traditional PIFs can achieve a wide frequency range of a strong absorption.