Isolation-Improved Dual-Band MIMO Antenna Array for LTE/WiMAX Mobile Terminals

A compact dual-band multiple-input-multiple-output (MIMO) antenna array with eight elements is proposed for the Long Term Evolution (LTE)/Worldwide Interoperability for Microwave Access (WiMAX) mobile applications. The dual-band MIMO array consists of four U-slit etched planar inverse-F antennas (PIFAs) and four L-slit etched PIFAs. The two types of PIFAs are placed orthogonally to reduce mutual coupling between them. With the presented decoupling methods in the design including the disconnection of ground plane, the parasitic resonant strips, and also the modified PIFAs, the excellent element isolation (above 20 dB) and other good MIMO performance are achieved. The overall dimension of the MIMO system is only 140 × 70 × 9.55 mm ³, and good return loss (above 10 dB) is achieved across the operating bands (2.6-2.8 and 3.4-3.6 GHz) for all the PIFA elements. The radiation patterns and envelope correlation coefficient (ECC) of MIMO system are also studied, showing quasi-omnidirectional radiation and accepted envelope correlation coefficient across the dual-band operation for mobile communications.