Design of an Energy Selective Reflectarray Antenna for Adaptive Prevention of High-Intensity Radiation Fields

This paper presents an energy selective reflectarray antenna with field-induced gain to prevent the high-intensity radiation fields (HIRF) in the X-band. Each unit cell of the reflectarray was anti-parallelled loaded with two diodes, the status of which could adaptively change the reflection phase according to the field intensity. When the diodes were all in the OFF-state, the unit cells in the reflectarray followed the gradient phase distribution, forming a high-gain beam; once there were diodes triggered by induced voltage caused by the high intensity incident wave, the gradient phase distribution was unsatisfied so that the reflected wave would be diffused and the gain would decrease. After full-wave simulation, the prototype was manufactured and measured in both the high- and low-intensity environments. The simulation and measurement results indicate that when the electric field strength is below 100 V/m, the achieved gain is above 25 dBi, the 1 dB bandwidth is 5.6% and the aperture efficiency is 29%; in the case of HIRF's illumination, the gain decreased by more than 20 dB within a bandwidth of 700 MHz. This dual-functional design holds significant promise for protecting sensitive payloads in aerospace platforms and improving signal integrity in radar systems exposed to electromagnetic interference.