Grating Lobe Suppression of Large Element Spacing Array by Angle Selective Surface

In this letter, a large element spacing array antenna with a regular square lattice and simple structures is proposed, which adopts a simple grating lobe suppression approach by loading rectangular cavities and an angle selective surface. The proposed array antenna can achieve ±15° scanning in the H-plane with active VSWRs below 2.5 within 9.2–10 GHz and has an element spacing of 0.96
λ_c
(where
λ_c
is the free-space wavelength at the center operating frequency, i.e., 9.6 GHz). Additionally, the utilization of rectangular cavities and the angle-selective surface effectively reduces the gains of the grating lobes by more than 13 dB compared to those of the main lobes. As a result, the gains of the grating lobes are at the same level as those of the first sidelobes, indicating a good grating lobe suppression effect. Finally, a 7 × 5 array prototype is fabricated to validate the proposed design, and a good agreement is achieved between the measured and calculated results.