Tri-arm MIMO array antenna pair for mobile phone applications

An 8 × 8 tri-arm multiple-input multiple-output (MIMO) array using novel even–odd mode decouplers is presented. To decouple the directly connected driven ports on the tri-arm antenna pair, a T-shaped stub working as an even-mode decoupler and a narrow strip working as an odd-mode decoupler are elaborately introduced. Therefore, the even-mode and odd-mode impedances cross with the antenna input impedance, and a deep coupling zero is achieved at this cross frequency. Finally, the proposed 8 × 8 MIMO array was developed, fabricated, and measured for further performance verification. The measured results show that the proposed array can have a wide isolation bandwidth of 17.2 % with a compact size of 0.44λ 0 × 0.08λ 0 and zero clearance requirement on the ground plane. The diversity performances are also investigated with the measured worst envelope correlation coefficient less than 0.05.