Development of Adaptive Array Antenna for Mobile Handsets

随着近年来高速通信网络的发展，也需要高速无线通信系统。然而，由于频率资源的限制，很难获得高速的无线系统。为了克服这个困难，需要将自适应阵列天线系统应用于移动的手机。本文分析了移动的手机天线间的互耦，并提出了互耦补偿技术。本文还研究了自适应阵列天线在移动的手机中抑制干扰信号的局限性.移动的手机天线间互耦的补偿对于互耦的补偿，提出了一种通过计算和存储互耦数据来获得阵元方向图的方法。通过数值仿真和实验验证了该方法的有效性.干扰抑制性能的限制的研究干扰抑制性能的评估使用的W-CDMA接收机的4元自适应阵列天线在2.45 GHz，这是由本研究人员开发的。用四元微带阵列天线对视距和非视距传播路径进行了实验，结果表明，对于视距情况，四分之一波长的阵列间距就足以抑制干扰。另一方面，当传播路径为非现场线时，阵列间距应大于半波长。还对具有2单元阵列天线的频域均衡器的接收机的干扰抑制性能进行了实验研究。

With the recent development of high-speed communications network, high-speed wireless communication system is also desired. However, it is difficult to obtain high-speed wireless system because of the limitation of frequency resources. In order to overcome this difficulty, application of adaptive array antenna system to mobile handsets is required. In the present research, mutual coupling among antennas mounted on a mobile handset has been analyzed and compensation technique of the mutual coupling has been developed. Limitation of the suppression of interference signal in the case of adaptive array antenna for mobile handsets has been also investigated.1. Compensation of mutual coupling among antennas mounted on mobile handset For the compensation of mutual coupling, a method, in which the data of mutual coupling are calculated and stored to obtain the array element pattern, has been developed. Numerical simulation of DOA (direction of arrival) estimation using array antennas composed of a monopole antenna and an inverted planar F-shaped antenna and experiments are performed confirming the validity of the proposed method.2. Investigation of limitation of interference suppression performance Performance of interference suppression is evaluated by using a W-CDMA receiver for 4 element adaptive array antenna at 2.45 GHz, which was developed by the present investigators. Experiment using 4 element monopole array antenna for line-of-sight and non-line-of-site propagation paths shows that a quarter wavelength array spacing is enough to suppress the interference for the case of line-of-sight. On the other hand, the array spacing should be longer than a half wavelength when the propagation path is non-line-of-site. Experimental investigation of the performance of interference suppression for a receiver having frequency domain equalizer for 2 element array antenna has been also performed.