A Wideband High-Efficiency Metal-Only Folded Reflectarray Using Subwavelength Detachable Trapezoidal Grooved Element

A wideband high-efficiency metal-only folded reflectarray antenna (FRA) using 3-D subwavelength detachable trapezoidal grooved element (SDTGE) is proposed in this communication. The presented element is made up of two orthogonally rectangular metal plates etched with two trapezoidal grooves. It allows the reflection phases of the two linearly polarized (LP) waves to be shifted independently by varying the lengths of the grooves. To make a detachable structure, a sliding groove is employed on one of the two metal plates to help assembly. By setting the period to a subwavelength, a smooth phase shift response is obtained to extend the bandwidth. In addition, a large reflection phase variation of 670° at 10.0 GHz and a low element loss of nearly 0 dB are obtained to further enhance the gain. Then, a
$35\times 35$
element reflective aperture spatially fed by a 3-D printed pyramidal horn antenna is designed and measured to verify the performance. The measured results exhibit that a wide 1-dB gain bandwidth of 26.5% is achieved. To reduce the profile, a wideband triple-layer polarization selector suspended on the reflective aperture is designed to achieve an FRA prototype. It features a maximum gain of 29.2 dBi corresponding to an aperture efficiency of 51.8% and a 3-dB gain bandwidth of over 34.2%. These results indicate that this metal-only FRA (MOFRA) has advantages of wide bandwidth and high efficiency.