Design and experimental validation of dual-feed cavity-backed slot antenna diplexer for millimeter-wave dual-band 5G applications

This article presents the development of a novel cavity-backed dual-feed miniaturized antenna with an intrinsic self-diplexing property for millimeter-wave dual-frequency 5G applications. The proposed device is designed using a rectangular substrate integrated cavity loaded with a K-shaped slot, which is powered by two 50 Ω feed lines to enable radiation at two millimeter-wave bands. The designable parameters of the K-shaped slot are used for independent frequency tuning. The impedance matching between the rectangular cavity and the feed lines is achieved by utilizing the inline feeding method. A basic design process, working approach, radiation methodology, and equivalent circuit analysis are all elaborated in depth. Finally, a prototype of the miniaturized antenna diplexer operating at 22 GHz and 27 GHz is fabricated and experimentally validated. The proposed antenna diplexer has a compact footprint of 0.448λ g 2 . The antenna prototype exhibits a return loss of − 25.7 dB (− 17.8 dB) and isolation greater than 31.2 dB (25.1 dB) at 22 GHz (27 GHz). The antenna prototype achieves EM and measured realized gains exceeding 4.38 dBi (4.23 dBi) and 4.1 dBi (4.27 dBi), with efficiencies better than 88% and 83% at 22 and 27 GHz, respectively. The proposed antenna diplexer offers a low cross-polarization level well below − 30 dB at both millimeter-wave bands. Additionally, the antenna enables wide frequency tunability ranging from 21.85 to 22.15 GHz and from 21.85 to 22.15 GHz around 22 and 27 GHz, respectively, which makes it a suitable device for dual-band millimeter-wave systems. Furthermore, the proposed design supports Sustainable Development Goal (SDG) 9 by advancing innovative and energy-efficient communication infrastructure for future millimeter-wave 5G applications. Furthermore, the proposed design supports Sustainable Development Goal (SDG) 9 by advancing innovative and energy-efficient communication infrastructure for future millimeter-wave 5G applications.