A Design for a Wide-Band Antenna Pair Applied for Mobile Terminals at the Sub-6 GHz Band

To meet the requirements of a high transmission rate and strong communication quality for mobile terminals, a planar antenna printed on a 0.8-mm-thick FR-4 substrate is proposed in this paper. The structures are compact, with a size of 23×6 mm2. The performance of a single antenna pair in a 75×35 mm2 ground plane shows the advantages of both ultra-wide bandwidth and high isolation. The operating frequency of −6 dB is 54% (3.3 GHz–5.9 GHz). To solve the mutual coupling effects exiting in the antenna pair, a hybrid strip defected grounding structure (DGS) is added in the middle of neighboring antenna elements, and good isolation performance of lower than −13 dB is achieved. The evolution and analysis of the proposed antenna pair are given to investigate the operating principle. To verify its practicality, an eight-port antenna system in 150×70 mm2 ground plane is constructed along two frames of the smartphone board. The MIMO antenna system performance is simulated and texted. The results show a bandwidth of 3.4–5.2 GHz (−6 dB), an isolation performance lower than −10 dB, an ECC lower than 0.01, and a total efficiency of 46–84%. In addition, the performance of the antenna system under single handheld conditions is also discussed. The correlation results show that the designed antenna pair has good data transmission and interference resistance capability, which proves that this is an excellent antenna model for application in mobile terminals.