부산대학교 도서관

A cavity-backed slot-antenna (CBSA) pair is designed in a shared cavity inserted with the multifunctional metasurface diaphragms (MSDs). The CBSA pair is co-polarized and in-band, and meanwhile exhibits the good features of a wide working band, good in-band decoupling, and enhanced out-of-band filtering performance, which are rarely achieved in other reported CBSAs. The customized MSDs in this design can introduce desired reflection/transmission properties and provide shorting paths in the cavity, which play an important role in adjusting the frequencies of the resonance modes to expand the working bandwidth, allowing proper transmission magnitudes and phases at different frequency points to enable the high isolation level, and generating filtering responses to introduce the radiation nulls (RNs) and enhance the out-of-band suppression. The proposed CBSA pair was analyzed, and then fabricated and measured. The total electrical size at the lowest working frequency $\text{f}_{L}$ is $0.76\times 0.58\times 0.16\lambda _{L} ^{3}$ . The overlapped fractional impedance bandwidth is $\sim $ 11.1%. The peak realized gain (RG) reaches 6.4 dBi, and the isolation is greater than 15 dB. The three introduced RNs guarantee the out-of-band suppression level is better than 14.6 dB in 6–15 GHz. The proposed CBSA pair is a good candidate for the compact, co-polarized, in-band, and high-efficiency multiple-input-multiple-output (MIMO) CBSAs.