A Novel Method for the Low-detectable Dihedral Corner Utilizing Phase Gradient Metasurface based on Phase Cancellation Mechanism

In this paper, a phase gradient metasurface (PGM) is proposed to reduce the radar cross-section (RCS) of the dihedral corner based on phase cancellation mechanism. The phase cancellation mechanism is used to derive the formula of the low-detectable dihedral corner for the first time, which is directly used to deal with the wave path difference problem that introduced by the dihedral corner. According to the formula, six sub-cells are designed with a 60∘ phase difference, which is arranged by sub-array along the y-axis. The reflection coefficients of the selected sub-cells are all above 0.8. The RCS reduction of the dihedral corner achieves over 10 dB from 4.9 GHz to 5.14 GHz under an incident angle of 45∘. In particular, the RCS reduction of the low-detectable dihedral corner is 13.97 dB at 5 GHz. Meanwhile, the proposed dihedral corner with PGM also has an excellent performance of angle insensitivity ranging from 0∘ to 75∘. To further verify our design, the dihedral corner with PGM is manufactured by a low-cost printing circuit board technique. The measured results agreed well with the simulations, and both of them show an excellent performance of RCS reduction in the operating frequency band, regardless of any angle within 75∘. Overall, the dihedral corner with PGM that we proposed has the advantages of being low-detectable, low-profile, low-cost, lightweight, and it is easy to design and manufacture. It has wide application prospects in the future.