A Wideband Low-RCS Transmitarray With High Aperture Efficiency Based on Grooved Metasurface

In this letter, a novel grooved metasurface (MS) is proposed to realize a wideband low radar cross section (RCS) transmitarray with high aperture efficiency. Through grooving on a MS, the radiation performance of the wideband low-RCS transmitarray can be improved. For transmission characteristic, the MS can provide a higher transmission amplitude in a wide bandwidth by grooving. For reflection characteristic, the MS produces a gentle reflective phase curve. The designed grooved MS can be used to achieve high-performance radiation and scattering performance simultaneously. A prototype is fabricated and measured. Measurements reveal that the -3 dB gain bandwidth is 35.3% from 14 to 20 GHz, with a peak gain of 23.9 dBi at 18 GHz and a maximum aperture efficiency of 54% at 17 GHz. Compared with an ungrooved transmitarray, the -1 dB gain bandwidth of the grooved transmitarray has been improved from 16.7% to 22%, while the aperture efficiency has been improved from 47% to 57%. Meanwhile, the 10 dB monostatic RCS reduction bandwidth is 50% (from 11.6 to 19 GHz) for y-polarization and 98% (from 9.2 to 27 GHz) for x-polarization, respectively. This wideband transmitarray with high aperture efficiency and low scattering properties has practical application value in radar system.