In‐band radar cross‐section reduction of the slot array antennas by RAM‐based frequency selective surfaces

Abstract

Abstract A method for reducing radar cross‐section (RCS) of the slot array antenna by utilising the radar absorbing material, while preserving the radiation performance simultaneously, is proposed and discussed. The scheme is based on the implementation of the multilayer frequency selective surface‐radar‐absorbing material (RAM) capable of operation over a wide frequency band. The use of radar absorbing material on an antenna’s radiation screen causes a change in surface current, resulting in the radiation pattern of the antenna. Therefore, by designing the coating pattern of the radar absorbent material as a substrate and a capacitive patch as a unit cell on the antenna board, the reduction of 19 dB RCS at X‐band and minimum antenna gain loss (3dB) is achieved. To demonstrate the proposed solution, a 30‐cm diameter slot array antenna, which is considered as a test case, is coated by RAM and radar cross section reduction (RCSR) is dramatically accomplished over a frequency band ranging from 8 to 12 GHz. It is worth mentioning that the obtained RCSR at 9.4 GHz is as much as 19 dB. Subsequently, the proposed method can be a candidate for reduction of RCS in slot array antennas, considering the remarkable RCSR and acceptable effect on radiation characteristics.