A Low-Scattering Vivaldi Antenna Array With Slits on Nonradiating Edges

To reduce in-band scattering over a large angular range, this communication presents a low-scattering Vivaldi antenna array with cutting slits on the nonradiating edges of each antenna element. Over-concentrated overlap between structural modal and antenna modal scattering currents motivates the novel slit design over the nonradiating edges. These slits separate the structural modal and antenna modal scattering currents in the largest extent. The structural modal scattering is then suppressed through a cavity like structure in the nonradiating portion, while the antenna modal scattering currents keep unchanged as they are crucial for the radiation performance. The design features with a simple structure, while effectively reduces the in-band radar cross section (RCS) in a wide angular range of +/- 70 degrees and achieves +/- 60 degrees scanning in the E-/H-planes over the entire X-band. Prototypes for the proposed 8 x 8 Vivaldi antenna array and a reference conventional Vivaldi antenna array are fabricated, assembled, and measured. Both measured and simulated results demonstrate the effectiveness of the low-scattering Vivaldi antenna array design.