Design and fabrication of broadband radar metamaterial absorber based on the resistor FSS

Abstract

In this paper, a kind of composite radar absorption materials, consisting of polygonal and seamed resistor with frequency selective surface (FSS) and traditional magnetic radar absorption materials (RAM), is presented. After analyzing such a material and its topological structure, we obtain the equivalent circuit model of this structure, and acquire the reflectivity and input impedance of such models on the basis of transmission line theory. By the application of CST (computer simulation technology), we have made a comparison between structures with nonresistor and resistor FSS. The structure with resistor FSS has a dual-band whose bandwidths are 0.8 GHz from 8.4 to 9.2 GHz and 0.22 GHz from 11.5 GHz to 11.72 GHz with the reflectivity below-10 dB, respectively. The simulated reflection coefficient for the resistor FSS shows two resonant frequencies at 8.7 and 11.5 GHz which respectively make contribute to a higher absorbing peak reaching-24 dB and-23 dB. However, the nonresistor FSS does not have the absorption peak at 8.7 GHz, and the absorption peak at 11.5 GHz reaches-20 dB, confirming the importance of resistors in improving absorption performance. We have observed which part of such a structure influences amost the bsorption by ascertaining power loss density in the absorbing structure. Based on the current distribution of the FSS, two different schemes of LC equivalent circuits can be modeled, at 8.7 GHz and 11.5 GHz, which can explain the anti-resonance and higher absorbing peak of resistor FSS. Moreover, due to the fact that the induced current increases significantly after adding resistors, we could see that the losses happen when the induced current flows through the resistors, Finally the usage of resistor could improve the absorptive performance of FSS at around 8.7 GHz, this result is coincident with that of simulation. In addition, the combination of resistor FSS and RAM can lead to a frequency-doubling effect, meaning that it has remarkable absorptive performance in the range of 8–15 GHz.