Adaptive coherent power combiner

This paper summarizes advances in liquid-crystal technology for use as tunable phase-delay lines. The amount of phase delay through the liquid crystal is adaptively tuned, in order to coherently combine two signals, regardless of their phase differences. By adaptively adjusting the phase delays in the two signal paths, maximum coherent power combining is ensured. This ability to coherently combine the power of two signals regardless of their initial phase differences can greatly simplify antenna-diversity techniques used in MIMO applications.