Dual-Band Shared-Aperture Antenna with Bifunctional Metasurface

A dual-polarized dual-band antenna with a simple bifunctional metasurface (MS) is proposed. Previous studies often require various elements to design MSs, and most monofunctional MSs are designed to control one intrinsic property of electromagnetic wave. In contrast, the proposed MS uses only one type of element to realize dual functions. In the lower frequency band, the MS helps to excite the TM leaky-wave mode and together with the slot mode to obtain a wide bandwidth of 25.8%. In the higher frequency band, the MS functions as a frequency selective surface to enhance the antenna gain by 6 dB and decreases the distance between the MS and the patch antenna to 0.1 wavelength. By composing the antenna with a pair of stub-loaded slots and a rectangular patch sharing the same ground and diamond-shaped MS, dual bands and dual polarizations are obtained. The MS antenna is first simulated, and then fabricated and measured. The proposed antenna demonstrates the operating bands of 2.12-2.75 GHz (0.63 GHz, 25.8%) for Port 1 and 5.69-5.91 GHz (0.22 GHz, 3.8%) for Port 2, with peak boresight gains of 7.9 dBi at 2.7 GHz and 11.7 dBi at 5.75 GHz.