Large Element Spacing Array Antenna in Square Lattice Based on Angle Selective Surface

A square lattice array antenna with a large element spacing is proposed in this paper, which can achieve an operating bandwidth from 9.2 to 10 GHz with active VSWRs below 3 for scanning angles up to ± 15° in the H-plane. The element spacing of the proposed antenna is 30 mm, which corresponds to a free space wavelength at the highest operating frequency. To effectively suppress the grating lobes resulting from the large element spacing, an angle-selective surface composed of square annular slots is loaded at a specific height above the radiation structures in the proposed antenna. Consequently, the gains of the grating lobes are more than 13 dB lower than those of the main lobes, reaching a similar level as the first sidelobes. Additionally, the proposed antenna offers the advantages of regular port arrangements and simple structures.