Broadband Dual-Polarized Antenna Using Metasurface for Full-Duplex Applications

In this letter, a broadband dual-polarized metasurface-based antenna is proposed for in-band full-duplex applications. The design concept exploits the wideband and low-profile features of a metasurface, as well as its structural symmetry to implement the differential-fed scheme for high isolation. An antenna design operating at 3.5 GHz is optimized, fabricated, and tested. The prototype with dimensions of 0.97<inline-formula><tex-math notation="LaTeX">$\lambda _{\text{min}}$</tex-math></inline-formula> × 0.97<inline-formula><tex-math notation="LaTeX">$\lambda _{\text{min}}$</tex-math></inline-formula> × 0.078<inline-formula><tex-math notation="LaTeX">$\lambda _{\text{min}}$</tex-math></inline-formula> (<inline-formula><tex-math notation="LaTeX">$\lambda _{\text{min}}$</tex-math></inline-formula> is the free-space wavelength referring to the lowest operational frequency) achieves a 10 dB return loss bandwidth of 28.4% (2.93–3.90 GHz) and an interport isolation of <inline-formula><tex-math notation="LaTeX">$>$</tex-math></inline-formula>43 dB. The far-field measurements indicate that the antenna exhibits broadside radiation with a realized gain of <inline-formula><tex-math notation="LaTeX">$>$</tex-math></inline-formula>8.0 dBi and low cross-polarization level of <inline-formula><tex-math notation="LaTeX">${<}-$</tex-math></inline-formula>30 dB within the wide operational bandwidth.