Shared Aperture Wideband Endfire/Broadside mm-Wave Phased Array With Enhanced Scanning Range Integrated With Metal Frame for Mobile Terminals

A shared aperture wideband endfire/broadside millimeter-wave (mm-Wave) phased array and a novel method to effectively enhance the array scanning range are proposed for mobile terminals. The array element comprises an asymmetric open-ended cavity and a ground-slotted patch sharing the extended cavity surface for endfire and broadside radiation, respectively. The extended endfire cavity with an I-shaped slot can widen the working bands of both the endfire and broadside antennas. The proposed $1\times 4$ mm-Wave phased array can fully cover the desired 5G mm-Wave N257 and N258 bands with a compact size of only $0.54\times 2.15\times 0.18\lambda _{0}^{3}$ and a 3-dB endfire/broadside scanning range of ±45°/±46°. The integration ability, performance, and flexibility of the array with mobile terminals are further studied. The method of using the phased array to excite the frame current and enable the frame to take over the array for large-angle scanning is proposed. Based on this method, a shared aperture co-design of the mm-Wave array with a 4G long-term evolution (LTE) antenna is proposed. The mm-Wave broadside array in the co-design realizes a significantly enhanced scanning range of ±66° when integrated with the narrow terminal frame. For validation, the proposed mm-Wave array and its co-design are fabricated and tested with acceptable results. With the merits of extensive spatial coverage, wide bandwidth, compact size, and flexible terminal integration with enhanced scanning capability, the proposed mm-Wave phased array has application potential in future mobile terminals.