An Ultrabroadband Energy Selective Surface With Nonreciprocal Performance for HIRF Protection

In this article, a novel nonreciprocal energy selective surface (ESS) concept is proposed against high-intensity radiation field (HIRF) threat, which has unidirectional HIRF isolation performance in ultra-broadband. The nonreciprocal ESS consists of an electromagnetic (EM) detector, a controlling module, and a controllable surface. The EM detector is used to monitor the forward electric field. When HIRF irradiation comes from the front, the controllable surface is triggered by the detector from transparent to opaque, thus isolating the HIRF to protect the back-end sensitive equipment. On the contrary, the backward HIRF cannot trigger the controllable surface, thus ensuring that the HIRF can radiate out. To illustrate this concept, an ultrabroadband nonreciprocal ESS prototype is designed and fabricated. The results of the simulation and measurement prove that the designed ESS has low insertion loss for small signals and shows nonreciprocal high shielding effectiveness under HIRF. Furthermore, the ESS can work in an ultrabroadband covering 3.5–8.5 GHz. The proposed method can be used to protect HIRF-sensitive equipment that requires high-power EM radiation.