Effect of mutual coupling on the performance of adaptive antennas

Over the years, adaptive antenna arrays have received significant research efforts because of their ability to automatically null interference signals while maintaining a high signal-to-interference plus noise ratio (SINR) in the direction of the signal of interest (SOI). The research efforts have not only focused on developing new weighting algorithms, but also on understanding how the individual sensors (antennas in our case) and their distributions can affect the performance of adaptive antennas. The increasing demands for smaller and more efficient systems make it even more important to understand how the underlying electromagnetic characteristics of individual elements and antenna arrays affect the performance of adaptive antennas. As the antenna arrays become physically small, the mutual coupling between the antenna elements increases. The general view is that the increase in the mutual coupling inhibits the nulling capability of adaptive antennas, and one should try to minimize the coupling between antenna elements. In this work, we investigate the effect of mutual coupling on the performance of adaptive antennas operating in harsh interference environments. The physical size of the antenna is decreased while keeping the number of antenna elements fixed.