LAUSR

Inspired by the checkerboard metasurfaces, we propose the design of low-RCS multi-beam linearly polarized (LP) array antenna based on Pancharatnam–Berry (P-B) phase. The antenna array is composed of a number of split-ring resonators (SRRs) with a rotation angle $\alpha $ difference. For circularly polarized (CP) waves, each two adjacent SRRs exhibit $\alpha $ and $2\alpha $ P-B phase differences under feeding and normally illuminating, respectively. Because of this, the SRR array exhibits different phase gradients for radiated and reflected waves. To obtain multiple LP beams, reversed phase gradients for CP waves are alternatively arranged in 1-D or 2-D on the array, leading to two or four beams, respectively. Under normally illuminating, the reflection phases along the array form the checkerboard configuration, which can reduce both the in-band RCS and out-of-band RCS of the antenna array. As an example, we demonstrate a low-RCS four-beam antenna operating in ${X}$ -band. Both the simulated and measured results show that the maximal realized gain of each beam reaches up to about 13.6 dB at 10.2 GHz. To evaluate the RCS reduction performance, we measured specular reflection of the prototype under normal incidence. The reflection is reduced by more than 10 dB in 9.7–10.3 GHz and by more than 5 dB out-of-band in 10.3–14.0 GHz. The design method provides an alternative to the design of low-RCS and low-profile antenna arrays.