Enhanced diversity antennas for UMTS handsets

In this paper, we present several UMTS multi-antenna systems having radiators with low mutual coupling and high total efficiency. Firstly, two antennas are simply positioned at the top of a small ground plane whose size is representative of the Printed Circuit Board (PCB) of a mobile phone. A solution is then proposed to decrease their mutual coupling and enhance their total efficiency. Then the same neutralization technique is applied to a four-antenna structure. These systems are fabricated and measured. The simulated and measured S-parameters and total efficiencies are presented. The envelope correlation values are also shown and discussed. It is demonstrated that this neutralization technique could be easily implemented at the terminal side of a wireless link to achieve enhanced diversity antennas.