The Effects of Mutual Coupling on Performance of a Wideband Smart Antenna with Non-Uniform Components

1. Introduction With the rapid growth of various wireless services and applications calling for high data rate transmission there is a demand for developing robust wideband wireless technology. In order to counter count adverse phenomena such as multi-path signal propagation and interference, which become more pronounced in wideband systems, smart antennas can be employed as a remedy. So far, most of investigations have been devoted to narrowband smart antennas. Extending the smart antenna concept to wideband systems requires new research efforts. In the literature, three main concepts of wideband smart antenna system have been introduced, which include: space-time signal processing, space-frequency signal processing and fully spatial processing or space-only signal processing [1-3]. The advantages of the last wideband smart antenna concept are due to low complexity and low costs of practical realization. In [4-6], the authors proposed a wideband smart antenna using Non-Uniform Components (NUC). The investigations concerned the situation in which the mutual coupling between the array elements was neglected. In the present paper, we extend our considerations of the NUC wideband smart antenna system when the effect of mutual coupling between antenna elements is included. In particular, we investigate the mutual coupling effect on the radiation pattern and the signal-to-noise ratio (SNR). Comparisons are performed against a conventional uniform array antenna. The reminder of this paper is organized as follows. In Section 2, the configuration of a NUC wideband smart antenna is briefly described. In section 3, suitable expressions are derived to investigate the effect of mutual coupling on the conventional and NUC arrays radiation pattern and the SNR of a received signal. Section 4 presents results of computer simulations. Section 5 provides the discussion of these results. Section 6 concludes the paper.