Wideband Antenna Pairs Consisting of E-/M-Coupling Frame Monopoles and M-/E-Coupling Back Cover Patches for Mobile Terminal Applications

To address the contradiction between numerous antennas and tight space within a modern mobile terminal, wire-type co-frequency antenna pairs on the frame and planar-type patch antennas on the back cover have been research hotspots in recent years. To the best of the authors' knowledge, there is no work to study the relationship between wire-type frame monopoles and planar-type back cover patches. This article first proposes antenna pairs consisting of frame monopoles and back cover patches for mobile terminals. Monopole and half-mode patch act as the basic radiating elements, and their operation bandwidths are enhanced by using the electric-/magnetic-coupling (E-/M-coupling). The first antenna pair consists of the M-coupling monopole and E-coupling patch, while the second antenna pair consists of the E-coupling monopole and M-coupling patch. Both antenna pairs are with wideband performance. Ground booster effect is adopted in the second pair to achieve patch size reduction. Antenna isolation and irrelevance within each pair can be guaranteed attributing to the mode orthogonality of the E-/M-coupling antennas. Two antenna pairs operating at the 5G Wi-Fi band (5.15-5.85 GHz) are designed and the measured results demonstrate the feasibility. The proposed antenna pairs make full use of the limited space of the mobile terminal, are easy to constitute the $4\times4$ MIMO, and are suitable for two mainstream smartphones.