Design of an S-band ultra-wideband energy selective surface

In this paper, an energy selective surface (ESS) structure working in S-band is designed, which can realize ultra-wideband adaptive strong electromagnetic (EM) protection. The ESS is composed of top and bottom layers. The top layer includes two parallel strips and a patch, on which two PIN diodes are loaded, and the bottom layer includes two vertical stripes. When the incident EM intensity is lower than the threshold value, the ESS works in the transparent state, which makes the electromagnetic waves propagate; When the EM intensity exceeds the threshold value, the induced voltage generated between the metal strips and patch makes the PIN diode turn on, and the ESS enters the protective state and the electromagnetic wave is shielded. The working principle of the ESS is analyzed by simulating the surface current and electric field distribution in PIN diode on-off state and equivalent circuit model. The prototype was processed by PCB process and the insertion loss of weak field incident and shielding efficiency of strong field incident were measured. The experimental and simulation results are in great agreement. The results show that in the transparent state, the operating center frequency of the ESS is 2.7 GHz, and the operating band with insertion loss less than 1 dB is 2.2−3.5 GHz. In the protective state, the shielding efficiency of the operating band is greater than 10 dB, which meets the requirement of ultra-wideband.