Plasmonic absorbing structure using horizontal bent-wire array for low-frequency absorption enhancement

In this paper, a miniaturized scheme of plasmonic absorbing structure (PAS) is proposed which bends straight wire array into horizontal bent-wire array, contributing to outstanding low-frequency absorption enhancement. Our investigation shows that the interval of adjacent absorptions in spectrum can be efficiently reduced when the resonator of straight wire is developed into horizontal bent-wire in metamaterial absorber (MA). On illumination, an improved PAS consisting of horizontal bent-wire array and vertical wire array is proposed which can make full use of dispersion engineering for broadband absorption enhancement by virtue of spoof surface plasmon polariton (SSPP). Simulation and experimental measurement show that the proposed improved PAS can achieve broadband absorption with the efficiency more than 90% in the frequency band of 5.3-29.0 GHz, which is 40.8% lower in figure of merit compared with the original PAS. Our strategy provides an effective way to enhance the low-frequency absorption in a wider frequency band with no increase of total thickness, and we expect a wide range of applications to emerge from the proposed scheme.