Low RCS Antenna Array With Reconfigurable Scattering Patterns Based on Digital Antenna Units

In this communication, a low radar cross section (RCS) antenna array with reconfigurable scattering patterns based on digital antenna units is proposed. The digital antenna unit has two scattering states that are controlled by p-i-n diodes. For $y$ -polarized normally incident waves, the phases of the two reflected states exhibit a 180° phase difference at approximately 5 GHz. For $x$ -polarized incident waves, the antenna units act as meta-absorbers, and the incident power is absorbed by the antenna units. Moreover, the radiation properties of these two states are approximately the same at 5 GHz. Thus, the scattering patterns of the antenna array can be tuned by controlling the scattering states of the digital antenna units without affecting the radiation performance. By tuning the directions of the scattering pattern nulls to dynamically align to the direction of the incident wave, both the monostatic and bistatic RCS can be significantly reduced. An $8\,\, {\times }\,\,8$ antenna array was fabricated and measured to validate the proposed concept. The measured results are in good agreement with the simulated ones. This indicates that the proposed antenna array is a promising solution to address the challenges of bistatic radar systems.