Design of an optically transparent EMW structure with broadband-absorbing property

In this paper, an optically transparent electromagnetic window structure based on frequency selective absorber (FSA) technique is proposed with low-pass and high broadband absorbing property. The FSA consists of two resistive frequency selective surface layers and a low-passband layer, which are all designed using square ring structures. To make the whole design transparent, the traditional metal copper and resistors are replaced by indium tin oxide and the dielectric substrate by polyethylene terephthalate. The top and middle layers act as absorbing layers to generate broad absorption bands at high frequencies, while the bottom layer is used to generate low-pass transmission bands. The simulation results show that the insertion loss is less than 3 dB below 3.6 GHz, while the absorption bandwidth covers 6-18 GHz with an angular stability reaches 45 degrees.