A Wideband U-Shaped Slot Antenna and Its Application in MIMO Terminals

A wideband microstrip multiple-input-multiple-output (MIMO) antenna with U-shaped slot is presented in this letter. To widen the impedance bandwidth, uniform and stepped U-shaped slot antennas are sequentially investigated. Two types of resonant modes are excited, including slot mode and monopole mode. Then, additional multiple slots embedded inside the U-shaped slot are employed to further widen the bandwidth. The proposed slot antenna features wide bandwidth (109%) and compact slot size ( 0.16λ
_g
×0.27λ
_g
, where λ
_g
is the guided wavelength at the lowest operating frequency) simultaneously. The proposed slot antenna element is then applied in the MIMO antenna system. Both the two antennas are suitable for handheld devices, covering GPS/GSM1800/LTE/UMTS/WLAN/WiMAX/UWB (lower) band.