Dual-Band Platform-Free PIFA for 5G MIMO Application of Mobile Devices

A dual-band platform-free antenna is proposed for the 5G multiple-input multiple-output (MIMO) application of mobile devices. The antenna is formed by adding a vertical metallic patch to the planar inverted-F antenna (PIFA) and setting another PIFA to feed the antenna by coupling. The vertical patch can effectively suppress the fringe currents on the ground plane, which makes the antenna electromagnetic compatible on different working platforms, e.g., the antenna is not affected by other components inside the real device and vice versa. The coupling feed helps to realize a dual-band operation and reduces the length of antenna to around
$\lambda $
/8, which makes the antenna more applicable in smartphones. As a design example, a handset MIMO antenna with eight elements is fabricated and measured. Furthermore, the throughput achieved by the antenna in an indoor environment is tested with an MIMO system developed by the Communication Laboratory of Huawei Corporation. The effect of one hand on the MIMO performance is also studied.