Wideband and wide-angle microwave absorber via an integrated frequency selective surface and lattice structure design

In this letter, a wideband microwave absorber with high angular stability is proposed based on the integrated design of frequency selective surface (FSS) and lattice structure. The proposed absorber is composed of a resistive FSS sheet embedded within two lattice structures. With the aid of the upper lattice structure, the wave impedance of the absorber is compensated at oblique incidence and the angular stable absorption is achieved. The performance of the absorber is investigated with an equivalent circuit model and full-wave simulations. The 80% and the 90% absorption bands are ranging from 1.4GHz to 6.2GHz and 1.5GHz to 6.1GHz, with a fractional bandwidth of 126.3% and 121%, respectively. Meanwhile, the absorption rate keeps above 80% within 65° for both TE and TM polarizations and remains above 90% within 50° incident angle. For further verification, a prototype has been fabricated and measured. Good agreements between the simulated and measured results can be observed. Considering the wideband absorption characteristics and high angular stability, the proposed absorber can be applied to construct EM wave shelters.