Design of pattern diversity antenna for mobile communications

In a multipath fading mobile environment, reliable communications can be achieved by the techniques of diversity reception. Diversity schemes provide two or more inputs at the mobile reception unit or base station in such a fashion that the fading phenomena at these inputs are nearly uncorrelated. After reception, these inputs can be combined so that the fades are smoothed out before the message is detected. Several types of diversity schemes have been proposed and utilized. In particular, space and frequency diversity systems are popular but require either a large space or extra frequency spectra. We consider the implementation of a pattern diversity receiver using antenna arrays. In conventional pattern diversity receivers, one employs two collocated antennas having different response patterns. The main disadvantage of this technique is the lack of adaptation in response to the environment because the patterns are essentially fixed. Our goal is to develop an adaptive pattern diversity system which can adapt the beam patterns in an optimum way as the communication channel varies.