A Study of Ultra-Thin Single Layer Frequency Selective Surface Microwave Absorbers With Three Different Bandwidths Using Double Resonance

In this paper, we present three ultra-thin frequency selective surface (FSS) microwave absorbers on a single layer, that have three remarkable features. First, the various absorbing bandwidths can be obtained in our absorber by adjusting the two absorbing peaks, which are produced by two different resonance effects on the FSS. By manipulating the dimension parameters, we design the dual-band, 3-dB and 10-dB band absorbers. We achieved the absorber´s thickness of 0.039λ_g with the single layer due to high loss of inter-digital capacitor patterns on the FSS. Additionally, the proposed absorbers are insensitive to polarized electromagnetic (EM) waves because of the symmetric structure of the FSS. In this study, the absorber mechanism and transmission line (TL) modeling for the absorber design are studied. Each of the proposed absorbers is analyzed by using the TL equivalent circuit model and full-wave analysis. The loss factor is studied in order to demonstrate the origin of losses, and a parametric study is conducted to explain how to vary the absorbing bandwidths. The performances of each proposed absorber are also experimentally demonstrated.