Performance comparison and improvement in adaptive arrays based on time- and frequency-domain signal processing

It has been known that an adaptive array antenna is effective for reducing frequency-depending selective fading, which is a problem in wide-band land-mobile communication systems. In an environment in which many delayed signals arrive, it is desirable to improve their SN ratio by using co-phase synthesis. There have been two types of adaptive array antenna for this purpose: an antenna based on time-domain signal processing using a TDL (tapped delay line), and an antenna based on frequency-domain signal processing using a fully reconfigurable filter. The latter has variations in its configuration, and is useful for making practical apparatus. However, its convergence process and behavior in a fading environment have not been clearly understood. In this paper, the performance and the advantages and disadvantages of adaptive array antennas based on various configurations with time- and frequency-domain signal processing are compared. It is found that combinations of some configurations improve their performance. The improvement in performance is also described. (C) 2002 Wiley Periodicals, Inc.